docs: revise contribution guidelines for clarity and inclusivity

[aofei]

As our project grows, we want to ensure that our community understands how to contribute effectively and feels welcomed to do so. This update to our contribution guidelines aims to clarify the process and encourage more developers to get involved.

Key changes include:

• Simplified the language to make the guidelines more accessible to non-native English speakers and newcomers to open source.
• Included a step-by-step guide on setting up the development environment, submitting a pull request, and what to expect during the review process.
• Added a new section on community standards and code of conduct to foster a respectful and inclusive community atmosphere.
• Provided clear examples of desirable contributions, such as bug fixes, feature proposals, and documentation improvements.

Updates #1829

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There may be more content to add here, but I've written down the main points as a foundation. I suggest giving it a thorough read before merging.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.57%. Comparing base (0a7dbfe) to head (bfae6ef).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1831   +/-   ##
=======================================
  Coverage   92.57%   92.57%           
=======================================
  Files          42       42           
  Lines       11418    11418           
=======================================
  Hits        10570    10570           
  Misses        686      686           
  Partials      162      162           

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