feat: support new agents tasks and customizing environment guide

[Gaiejj]

Description

• docs(README): add customizing environment example
• feat: support Doggo and Raceacar agents tasks

Motivation and Context

An issue raised in discussion about environment customizing. We update the answer in README as well.

Safety-Gymnasium has supported new agents Doggo and Racecar and we add them in the register as well. The performance curves and tables would be coming soon in future pull requests.

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)

[codecov-commenter]

Codecov Report

Merging #256 (d7a78a7) into main (19f7fc7) will not change coverage.
The diff coverage is n/a.

❗ Current head d7a78a7 differs from pull request most recent head 854c71a. Consider uploading reports for the commit 854c71a to get more accurate results

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@@           Coverage Diff           @@
##             main     #256   +/-   ##
=======================================
  Coverage   97.01%   97.01%           
=======================================
  Files         138      138           
  Lines        6990     6990           
=======================================
  Hits         6781     6781           
  Misses        209      209           

Files Changed	Coverage Δ
omnisafe/envs/safety_gymnasium_env.py	97.96% <ø> (ø)

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[muchvo]

LGTM.

[muchvo]

LGTM.