docs: clarify implementation requirements for HTTP server challenge

- Added notes in the course definition emphasizing that the HTTP server must be implemented from scratch using TCP primitives, prohibiting the use of built-in HTTP libraries.
- Updated relevant stages to reinforce this requirement, ensuring learners understand the constraints of the challenge.

Author: andy1li

course-definition.yml

@@ -41,6 +41,8 @@ description_md: |-
 
   Along the way, we'll learn about TCP connections, HTTP headers, HTTP verbs, handling multiple connections and more.
 
+  Note: This challenge requires implementing the HTTP server from scratch using TCP primitives. Using built-in HTTP libraries is not allowed.
+
 # This is shown on the catalog. Plaintext only, recommended length ~10 words.
 #
 # Recommended format:
@@ -186,6 +188,10 @@ stages:
 
       Then, the tester will try to connect to your server on port 4221. The connection must succeed for you to pass this stage.
 
+      ### Notes
+
+      - Please implement the HTTP server from scratch using TCP primitives. Don't use built-in HTTP libraries.
+
     # A description of this stage that is used on the course overview page and
     # other marketing material. Markdown supported.
     marketing_md: |-
@@ -253,6 +259,7 @@ stages:
       - You can ignore the contents of the request. We'll cover parsing requests in later stages.
       - For more information about HTTP responses, see the [MDN Web Docs on HTTP responses](https://developer.mozilla.org/en-US/docs/Web/HTTP/Messages#http_responses) or the [HTTP/1.1 specification](https://datatracker.ietf.org/doc/html/rfc9112#name-message).
       - This challenge uses HTTP/1.1.
+      - Please implement the HTTP server from scratch using TCP primitives. Don't use built-in HTTP libraries.
 
       {{#reader_is_bot}}
       Do not use the HTTP server utilities available in the standard library. Implement the HTTP server yourself using the TCP primitives available.