docs(readme): update readme and contributing guidelines

[donch1989]

Because

• the readme and contributing guidelines are outdated

This commit

• update readme and contributing guidelines

[linear]

INS-2042 add contribution guidelines in pipeline-backend

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (066682d) 0.00% compared to head (52a642c) 0.00%.
Report is 2 commits behind head on main.

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Additional details and impacted files

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  Files          7       7           
  Lines       1842    1842           
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  Misses      1842    1842           

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unittests	0.00% <ø> (ø)

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