Add incipient documentation tooling

[tatiana]

This PR introduces an incipient version for documentation tooling in DAG Factory.

It introduces three requirements to create/generate documentation:

• Mkdocs (tool recommended by the Astronomer docs team)
• Mike (for documentation versioning)
• pymdown-extensions (so we can leverage Snippets for injecting code from other files inline in the Markdown files)

Also, it introduces three new hatch commands:

• hatch run docs:build: builds the docs locally, generating the correspondent static HTML website;
• hatch run docs:serve: builds and serves the docs locally at localhost:8080;
• hatch run docs:release: creates a version release using the version specified in dagfactory/__init__.py using Mike

This screenshot illustrates versioning:

This screenshot illustrates code snippets:

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.29%. Comparing base (c171166) to head (db38d53).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #328   +/-   ##
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  Coverage   93.29%   93.29%           
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  Files          10       10           
  Lines         776      776           
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  Hits          724      724           
  Misses         52       52           

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[tatiana]

We just realised that this is publishing to GH pages 🙈
We'll fix this as part of #279