Update AEC & Parallel docs to include examples, fix all docs links to use sphinx links

[elliottower]

This allows the links to work with different docs versions (i.e., if you use main (unstable) it will link to a page with the same version, instead of always going to the most recent release when you click a link). Also adds some examples just for people to have an idea of what parallel envs are good to start with, and makes the AEC and Parallel API pages a bit more consistent and easy to read.

Description

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Fixes # (issue), Depends on # (pull request)

Type of change

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

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Checklist:

• I have run the pre-commit checks with pre-commit run --all-files (see CONTRIBUTING.md instructions to set it up)
• I have run pytest -v and no errors are present.
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I solved any possible warnings that pytest -v has generated that are related to my code to the best of my knowledge.
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes