Italian translation of contributing.md

[csr]

This PR translates the contributing.md to Italian. This page was added to the configuration mkdocs.yml file.

Related to #1556.

[codecov]

Codecov Report

Merging #1836 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master     #1836   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          235       235           
  Lines         6989      6988    -1     
=========================================
- Hits          6989      6988    -1     

Impacted Files	Coverage Δ
fastapi/params.py	100.00% <0.00%> (ø)
fastapi/encoders.py	100.00% <0.00%> (ø)
fastapi/exceptions.py	100.00% <0.00%> (ø)
fastapi/applications.py	100.00% <0.00%> (ø)
fastapi/security/http.py	100.00% <0.00%> (ø)
fastapi/param_functions.py	100.00% <0.00%> (ø)
fastapi/security/api_key.py	100.00% <0.00%> (ø)
fastapi/dependencies/utils.py	100.00% <0.00%> (ø)
fastapi/dependencies/models.py	100.00% <0.00%> (ø)
tests/test_jsonable_encoder.py	100.00% <0.00%> (ø)
... and 1 more

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[github-actions]

📝 Docs preview for commit ca78bc2 at: https://5f293401dc0ccbc9ca32c76b--fastapi.netlify.app

[csr]

I'm not actively participating in the translation efforts any longer but I would encourage you to create a separate pull request.