doc(contribution-guide): add guidelines for issues closed to community pickup (#222)

## Description
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[adds/removes/fixes/replaces] the [feature/bug/etc] -->

This pull request updates the `CONTRIBUTING.md` file to clarify which
issues are not open for community assignment and adds guidelines for
interacting with such issues. The goal is to help contributors
understand when they should not request assignment or submit pull
requests for certain labeled issues.

**Updates to issue assignment guidelines:**

* Added a new section describing the `maintainers-only` and `wontfix`
labels, explaining that issues with these labels are not open for
general contributor assignment and specifying the reasons behind these
restrictions.
* Provided clear guidelines on how to interact with issues labeled as
unavailable, including advice on asking for clarification and suggesting
alternative approaches.

## Related Issue
<!-- Please prefix the issue number with Fixes/Resolves - example: Fixes
#123 or Resolves #123 -->

NA

## Screenshots/Screencasts
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changes (especially if it's a visual change) -->

NA

## Notes to Reviewer
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information that can help reviewer better review you changes -->

NA

Author: babblebey

CONTRIBUTING.md

@@ -65,6 +65,19 @@ If you wish to work on an open issue, please ask for it to be assigned to you an
 
 In case you get stuck while working on an issue you've been assigned, feel free to ask question openly in the comment.
 
+#### Labels Closed to Community Pickup
+
+Some issues are intentionally not open for general contributor assignment:
+
+- `maintainers-only`: Requires core team context, elevated permissions (infra, secrets, deployment), or involves architectural refactors in progress. Do not ask to be assigned or open a PR unless a maintainer explicitly invites help.
+- `wontfix`: We are not taking action on this (currently or possibly ever) due to priority, scope, strategy, or technical constraints. Constructive discussion is welcome, but please do not submit a PR “just fixing it” while this label remains.
+
+Guidelines:
+
+1. If an issue has one of the above labels, treat it as unavailable even if it is unassigned.
+2. You may (once) ask politely for clarification if the rationale isn’t clear—keep it concise and respectful.
+3. If you think there is a smaller or alternative angle worth exploring, open a new issue or discussion rather than overriding the label.
+
 Please follow our [Code of Conduct](./code-of-conduct.md) in all your interactions with the project and its contributors.
 
 ### Pull Requests (PR)