docs: polish README, benchmarks and examples

[Gaiejj]

Description

Image title of off-policy benchmarks is wrong. This PR fix it.

Types of changes

What types of changes does your code introduce? Put an x in all the boxes that apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds core functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (update in the documentation)

Checklist

Go over all the following points, and put an x in all the boxes that apply.
If you are unsure about any of these, don't hesitate to ask. We are here to help!

• I have read the CONTRIBUTION guide. (required)
• My change requires a change to the documentation.
• I have updated the tests accordingly. (required for a bug fix or a new feature)
• I have updated the documentation accordingly.
• I have reformatted the code using make format. (required)
• I have checked the code using make lint. (required)
• I have ensured make test pass. (required)

[muchvo]

LGTM.

[codecov-commenter]

Codecov Report

Merging #246 (75b76a9) into main (18776f1) will not change coverage.
The diff coverage is n/a.

❗ Current head 75b76a9 differs from pull request most recent head 746838d. Consider uploading reports for the commit 746838d to get more accurate results

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@@           Coverage Diff           @@
##             main     #246   +/-   ##
=======================================
  Coverage   97.01%   97.01%           
=======================================
  Files         138      138           
  Lines        6994     6994           
=======================================
  Hits         6785     6785           
  Misses        209      209           

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[muchvo]

LGTM.