add freecode camp tutorial to documentation

[Lee-W]

Description

as title

Checklist

• Add test cases to all the changes you introduce
• Run ./script/format and ./script/test locally to ensure this change passes linter check and test
• Test the changes on the local machine manually
• Update the documentation for the changes

Expected behavior

render the link to freecode camp documentation in Resources section

Steps to Test This Pull Request

1. poetry run mkdocs serve
2. open http://127.0.0.1:8000

Additional context

[codecov]

Codecov Report

Merging #475 (834159d) into master (308de9c) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #475   +/-   ##
=======================================
  Coverage   98.04%   98.04%           
=======================================
  Files          39       39           
  Lines        1431     1431           
=======================================
  Hits         1403     1403           
  Misses         28       28           

Flag	Coverage Δ
unittests	98.04% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
commitizen/commands/bump.py	95.19% <0.00%> (ø)

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