[Docs] improve contribute docs

[DenChenn]

Tracking issue

Related to #5783

Why are the changes needed?

Since Hacktoberfest is underway, I've updated the developer documentation to help them contribute easier.

Docs link

https://flyte--5862.org.readthedocs.build/en/5862/community/contribute/contribute_docs.html

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 36.72%. Comparing base (38af4ec) to head (d9fa47f).
Report is 18 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #5862   +/-   ##
=======================================
  Coverage   36.72%   36.72%           
=======================================
  Files        1304     1304           
  Lines      130072   130072           
=======================================
  Hits        47764    47764           
  Misses      78138    78138           
  Partials     4170     4170           

Flag	Coverage Δ
unittests-datacatalog	51.58% <ø> (ø)
unittests-flyteadmin	54.43% <ø> (ø)
unittests-flytecopilot	11.73% <ø> (ø)
unittests-flytectl	62.40% <ø> (ø)
unittests-flyteidl	6.89% <ø> (ø)
unittests-flyteplugins	53.62% <ø> (ø)
unittests-flytepropeller	42.84% <ø> (ø)
unittests-flytestdlib	54.78% <ø> (ø)

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