Update

Author: MatheusDS4

src/using-whack/dotenv.md

@@ -1,4 +1,4 @@
-The Whack project may include an [`.env` file](https://www.dotenv.org) that defines variables that may be
+The Whack project may include an [`.env` file](https://github.com/dotenv-rs/dotenv?tab=readme-ov-file#examples) that defines variables that may be
 referenced in `import.meta.env.NAME` expressions.
 
 > Note that an `.env` file applies to a Whack package's directory, and not a sole Whack workspace's directory per se.
@@ -15,4 +15,9 @@ ActionScript may read that `SECRET` variable using `import.meta.env.SECRET`:
 import.meta.env.SECRET
 ```
 
-> Note that `import.meta.env.NAME` returns `null` if `NAME` does not exist.
+> Note that `import.meta.env.NAME` returns `null` if `NAME` does not exist.
+
+## Syntax
+
+Refer to [this repository](https://github.com/dotenv-rs/dotenv?tab=readme-ov-file#examples) for supported syntax in
+`.env` files.