feat: Add root CONTRIBUTING.md to redirect users to official guide (Closes #11986)

[vannu07]

Added guidelines for contributing to the project.

What does this PR do?

| Add info |

IMPORTANT

• Read our contributing guidelines (I am adding a file to help others read it). [x] Is this a revision... (This is a new submission).
• Is this a revision of a previously submitted PR? If so, STOP! Go back, reopen the PR, and add commit(s) the branch you previously submitted. Please don't make the job of reviewing more difficult by hiding previous work.

For resources

N/A. This PR adds a documentation file (CONTRIBUTING.md) to the root, not a resource (book/course) to a list.

Description

This PR is related to repository maintenance and contributor guidance. I'm adding a root-level CONTRIBUTING.md file to redirect contributors to the official, detailed guidelines hosted in the docs/ folder. This specifically resolves the contributor confusion mentioned in Issue #11986.

Why is this valuable (or not)?

Valuable: It improves the discoverability of the contribution guidelines. New contributors landing on the GitHub page will instantly see the link to CONTRIBUTING.md in the sidebar and the file content, addressing the current confusion about where the rules are located. This saves maintainers time answering basic contribution questions.

How do we know it's really free?

N/A. This PR adds a documentation file, not a programming resource.

For book lists, is it a book? For course lists, is it a course? etc.

N/A. This PR adds a repository maintenance guide.

Checklist:

• Search for duplicates.
• Include author(s) and platform where appropriate.
• Put lists in alphabetical order, correct spacing.
• Add needed indications (PDF, access notes, under construction).
• Used an informative name for this pull request.
• N/A. The items in this checklist only apply to adding or modifying resource links, which this PR does not do.

Follow-up

• Check the status of GitHub Actions and resolve any reported warnings!

[Aniketh78]

(Not a maintainer) Hey, I have seen people create/modify new ".md" files, which are not appreciated in this repo. And also, the file you have created is too abstract. But yeah, good luck, pal.

[vannu07]

Thanks for the feedback, @Aniketh78!

I understand that new .md files are usually discouraged here, but I created this file specifically to address contributor confusion.

My PR is a targeted solution for Issue #11986 (No contribution file in root), and its purpose is to act as a concise redirect to the highly detailed, existing official guide: https://ebookfoundation.github.io/free-programming-books/docs/CONTRIBUTING.html

This makes the official rules instantly visible to new visitors in the GitHub UI sidebar, which should help reduce unnecessary PRs and save maintainer time.

Since all checks have passed, I hope the maintainers find this to be a valuable maintenance contribution!

[Aniketh78]

I want to make this clear! I never meant to discourage you or your contribution!, I'm sorry if it was conveyed that way. As far as I have seen, the maintainers are extremely helpful and guiding in this repository. I am in no place to tell you that you can't do certain things, I just told you what I have seen for the past few days on similar repo likes this. No hate!!.
Good luck and keep contributing!.

[vannu07]

I want to make this clear! I never meant to discourage you or your contribution!, I'm sorry if it was conveyed that way. As far as I have seen, the maintainers are extremely helpful and guiding in this repository. I am in no place to tell you that you can't do certain things, I just told you what I have seen for the past few days on similar repo likes this. No hate!!. Good luck and keep contributing!.

That's so kind of you to follow up, thank you! I genuinely appreciate the insider perspective—it helps me learn the unwritten rules of this large repo. Zero discouragement here, only motivation! Hope you have a successful Hacktoberfest!

[Aniketh78]

That means a lot! I'm happy to help. Wishing you a successful Hacktoberfest and a great future as well!