docs(nextjs): Move webpack build config under webpack namespace (#15691)

We are moving the only-webpack related configurations under `webpack`
namespace to better fit our goal of communicating the SDK readiness for
Turbopack by default.

This involved moving several options to be nested under a `webpack` path
in the build configuration.

This is meant to be released once this
getsentry/sentry-javascript#18343 goes live, so
I will keep this open until then. Will keep it in draft as well.

The SDK PR adds warnings for those deprecated options and warns users
about using them if detected so I don't think we need to do that here
once it goes live.

---------

Co-authored-by: Sarah Mischinger <sarah@codingwriter.com>

Author: logaretm

docs/platforms/javascript/guides/nextjs/configuration/build/index.mdx

@@ -182,50 +182,6 @@ Note: Enabling this option can lead to longer build times.
 
 </SdkOption>
 
-<SdkOption name="autoInstrumentServerFunctions" type="boolean" defaultValue="true">
-
-Automatically instrument Next.js data fetching methods and Next.js API routes with error and performance monitoring.
-
-</SdkOption>
-
-<SdkOption name="autoInstrumentMiddleware" type="boolean" defaultValue="true">
-
-Automatically instrument Next.js middleware with error and performance monitoring.
-
-</SdkOption>
-
-<SdkOption name="autoInstrumentAppDirectory" type="boolean" defaultValue="true">
-
-Automatically instrument components in the `app` directory with error monitoring.
-
-</SdkOption>
-
-<SdkOption name="excludeServerRoutes" type="Array<RegExp | string>">
-Exclude specific server-side API routes or pages from automatic Sentry instrumentation during build time.
-This option takes an array of strings or regular expressions and affects pages in the `pages` and `app` directories.
-
-When defining routes, note the following:
-
-- Specify pages as routes and not as file system paths. For example, write `/animals` instead of `pages/animals/index.js`.
-- Make sure that any provided string matches the route exactly, has a leading slash, and doesn't have a trailing slash.
-
-```javascript
-excludeServerRoutes: [
-  "/some/excluded/route",
-  "/excluded/route/with/[parameter]",
-  /^\/route\/beginning\/with\/some\/prefix/,
-  /\/routeContainingASpecificPathSegment\/?/,
-];
-```
-
-<Alert level="info">
-  If you're building your Next.js application with Turbopack, this option will
-  have no effect. The Sentry SDK will no longer apply build-time instrumentation
-  and will rely purely on Next.js telemetry features.
-</Alert>
-
-</SdkOption>
-
 <SdkOption name="tunnelRoute" type="string | boolean">
 <Alert level="info">
 This feature requires **Next.js version 11+** and doesn't currently work with self-hosted Sentry instances.
@@ -251,9 +207,18 @@ Learn more about tunneling in the <PlatformLink to="/troubleshooting/#dealing-wi
 
 </SdkOption>
 
-<SdkOption name="automaticVercelMonitors" type="boolean" defaultValue="false">
+<SdkOption name="useRunAfterProductionCompileHook" type="boolean" defaultValue="false(webpack)|true(turbopack)">
 
-Automatically create cron monitors in Sentry for your Vercel Cron Jobs if configured via `vercel.json`.
+<Alert level="info" title="Version support">
+  You can use this option with Next.js version 15.4.1 and later.
+</Alert>
+
+Enables the use of the [`runAfterProductionCompile` hook from Next.js](https://nextjs.org/docs/architecture/nextjs-compiler#runafterproductioncompile) to upload sourcemaps after the build is completed.
+
+- This option is set to `true` by default for Turbopack as there are no alternative ways to upload sourcemaps here.
+- This option is set to `false` for Webpack as the default behavior is to upload sourcemaps during the build process using the [Sentry Webpack Plugin](https://github.com/getsentry/sentry-javascript-bundler-plugins).
+
+**Important:** Enabling this option will mutate your Next.js build output by injecting [Debug IDs](/platforms/javascript/guides/nextjs/sourcemaps/troubleshooting_js/debug-ids/) via the Sentry CLI. If you are relying on any sort of integrity hashes for your build artifacts, you will need to disable this option.
 
 </SdkOption>
 
@@ -272,37 +237,59 @@ The route manifest is a build-time generated mapping of your Next.js App Router
 
 </SdkOption>
 
-<SdkOption name="reactComponentAnnotation.enabled" type="boolean" defaultValue="false">
+## Next.js Webpack Options
 
-Enables React component name tracking. When enabled, it annotates React components with data attributes that allow Sentry to track which components users interacted with in features like Session Replay and breadcrumbs.
+<Alert level="info">
+  These options only take effect if you're using Webpack. If you're using
+  Turbopack, these options will have no effect.
+</Alert>
+
+<SdkOption name="webpack.autoInstrumentServerFunctions" type="boolean" defaultValue="true">
+
+Automatically instrument Next.js data fetching methods and Next.js API routes with error and performance monitoring.
 
 </SdkOption>
 
-<SdkOption name="reactComponentAnnotation.ignoredComponents" type="string[] | undefined">
+<SdkOption name="webpack.autoInstrumentMiddleware" type="boolean" defaultValue="true">
 
-A list of React component names to exclude from component annotation.
+Automatically instrument Next.js middleware with error and performance monitoring.
 
 </SdkOption>
 
-<SdkOption name="useRunAfterProductionCompileHook" type="boolean" defaultValue="false(webpack)|true(turbopack)">
+<SdkOption name="webpack.autoInstrumentAppDirectory" type="boolean" defaultValue="true">
 
-<Alert level="info" title="Version support">
-    You can use this option with Next.js version 15.4.1 and later.
-  </Alert>
+Automatically instrument components in the `app` directory with error monitoring.
 
-Enables the use of the [`runAfterProductionCompile` hook from Next.js](https://nextjs.org/docs/architecture/nextjs-compiler#runafterproductioncompile) to upload sourcemaps after the build is completed.
+</SdkOption>
 
-- This option is set to `true` by default for Turbopack as there are no alternative ways to upload sourcemaps here.
-- This option is set to `false` for Webpack as the default behavior is to upload sourcemaps during the build process using the [Sentry Webpack Plugin](https://github.com/getsentry/sentry-javascript-bundler-plugins).
+<SdkOption name="webpack.excludeServerRoutes" type="Array<RegExp | string>">
+Exclude specific server-side API routes or pages from automatic Sentry instrumentation during build time.
+This option takes an array of strings or regular expressions and affects pages in the `pages` and `app` directories.
 
-**Important:** Enabling this option will mutate your Next.js build output by injecting [Debug IDs](/platforms/javascript/guides/nextjs/sourcemaps/troubleshooting_js/debug-ids/) via the Sentry CLI. If you are relying on any sort of integrity hashes for your build artifacts, you will need to disable this option.
+When defining routes, note the following:
+
+- Specify pages as routes and not as file system paths. For example, write `/animals` instead of `pages/animals/index.js`.
+- Make sure that any provided string matches the route exactly, has a leading slash, and doesn't have a trailing slash.
+
+```javascript
+webpack.excludeServerRoutes: [
+  "/some/excluded/route",
+  "/excluded/route/with/[parameter]",
+  /^\/route\/beginning\/with\/some\/prefix/,
+  /\/routeContainingASpecificPathSegment\/?/,
+];
+```
 
+</SdkOption>
 
+<SdkOption name="webpack.automaticVercelMonitors" type="boolean" defaultValue="false">
 
-</SdkOption>  
+Automatically create cron monitors in Sentry for your Vercel Cron Jobs if configured via `vercel.json`.
+
+</SdkOption>
 
 <SdkOption
-  name="unstable_sentryWebpackPluginOptions"
+  name="webpack.unstable_sentryWebpackPluginOptions"
   type="SentryWebpackPluginOptions"
 >
   Pass configuration options directly to the [Sentry Webpack
@@ -315,3 +302,15 @@ Enables the use of the [`runAfterProductionCompile` hook from Next.js](https://n
     in any release.
   </Alert>
 </SdkOption>
+
+<SdkOption name="webpack.reactComponentAnnotation.enabled" type="boolean" defaultValue="false">
+
+Enables React component name tracking. When enabled, it annotates React components with data attributes that allow Sentry to track which components users interacted with in features like Session Replay and breadcrumbs.
+
+</SdkOption>
+
+<SdkOption name="webpack.reactComponentAnnotation.ignoredComponents" type="string[] | undefined">
+
+A list of React component names to exclude from component annotation.
+
+</SdkOption>