Copy docs to package

[maryamziaa]

Proposed change(s)

Duplicate the docs from the webpage into the package. We're planning to use Unity Package documentation as the primary developer documentation and deprecate the maintenance of web docs.

Types of change(s)

• Bug fix
• New feature
• Code refactor
• Breaking change
• Documentation update
• Other (please describe)

Checklist

• Added tests that prove my fix is effective or that my feature works
• Updated the changelog (if applicable)
• Updated the documentation (if applicable)
• Updated the migration guide (if applicable)

Other comments

[amanda-butler-unity]

I left some suggested changes to fix some formatting errors. I also left some questions about whether some files should be added to the ToC.

[amanda-butler-unity]

This file isn't in TableOfContents.md. Is that intentional?

[maryamziaa]

This file is referred in Limitations.md which itself is in TableOfContents:

ml-agents/com.unity.ml-agents/Documentation~/TableOfContents.md

Line 43 in 63f6bb5

* [Limitations](Limitations.md)

ml-agents/com.unity.ml-agents/Documentation~/Limitations.md

Line 5 in 63f6bb5

- [`com.unity.mlagents` Unity package](Package-Limitations.md)

[amanda-butler-unity]

This file isn't in TableOfContents.md. Is that intentional?

[maryamziaa]

This file is referred in index.md

ml-agents/com.unity.ml-agents/Documentation~/Readme.md

Line 32 in 63f6bb5

- Quickly and easily add your own [custom training algorithm](Python-Custom-Trainer-Plugin.md) and/or components.