docs: improve clarity of docs and fix typo/grammar issues

[bearomorphism]

Closes #1405

Description

When I first started looking into how to use this tool, I found the documentation really hard to read.
It's such a pity for such a useful tool!

Thanks to powerful AI tools, improving clarity of the documents can be easily done.

• Rewrite README.md
• Rewrite contributing.md
• Fix several typos and grammar mistakes

Checklist

• Add test cases to all the changes you introduce
• Run poetry all 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

It should be easier for the readers to understand what Commitizen does after they enter the landing page of Commitizen.

The typo of the cli output should be fixed.

Steps to Test This Pull Request

NA

Additional context

NA

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.57%. Comparing base (120d514) to head (9b45d55).
Report is 606 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1404      +/-   ##
==========================================
+ Coverage   97.33%   97.57%   +0.23%     
==========================================
  Files          42       57      +15     
  Lines        2104     2680     +576     
==========================================
+ Hits         2048     2615     +567     
- Misses         56       65       +9     

Flag	Coverage Δ
unittests	97.57% <ø> (+0.23%)	⬆️

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[noirbizarre]

Thanks !

[Lee-W]

Niiiice! @bearomorphism but please use docs instead of fix in the commit type, we might need your help to rebase and modify the commit message. a fix commit will automatically bump a version which is not desired in this case

[bearomorphism]

@Lee-W But there's also a small behavioral change in cli.py. Is the change a fix or a docs?

[Lee-W]

@Lee-W But there's also a small behavioral change in cli.py. Is the change a fix or a docs?

I probably wouldn't consider it as a fix that we need to bump a version 🤔

[bearomorphism]

Ok let me rebase it, thanks

[bearomorphism]

Let me also fix #1405 in this PR to avoid catastrophic conflicts :)

[bearomorphism]

@noirbizarre @Lee-W I did a lot of changes in README after your latest reviews. Please kindly review my changes again when you have a moment. Thanks!

[bearomorphism]

I think we can probably automate this with GitHub workflow?

[bearomorphism]

@noirbizarre @Lee-W I did a lot of changes in README after your latest reviews. Please kindly review my changes again when you have a moment. Thanks!

I also rewrote contributing.md, please review