docs: fix invalid link, modify texts

[osrm]

Summary

• Fix invalid link and modify texts

Description

• Replaced the "Q&A discussions" link with the "XMTP Community Forums" link and label
• Updated bug report and feature request wording for clarity and consistency with other docs.
• This PR was updated with reference to https://github.com/xmtp/xmtp-js/blob/main/CONTRIBUTING.md

[macroscopeapp]

Update community engagement links and simplify contribution instructions in CONTRIBUTING.md

Updates the community engagement information in CONTRIBUTING.md:
• Changes the question link from GitHub Q&A discussion forum to XMTP Community Forums (community.xmtp.org)
• Removes detailed instructions about confirming existing issues and including reproduction steps for bug reports
• Removes detailed instructions about confirming existing issues and describing use cases for feature requests

📍Where to Start

Start with the changes in CONTRIBUTING.md to review the updated community engagement links and contribution instructions.

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Macroscope summarized af8b5a1.