Mkdocs deployment

[CBroz1]

This PR

1. Removes all docs-parts, as they are now folded into md versions of the original rst docs proposed to be kept in in an archive directory as part of datajoint-docs PR 18
2. Adds a doc contributor README with notes about vscode extensions that can aid in further contributions, including...
   • markdownlint for markdown linting
   • CSpell for spell checking
   • ReWrap for hard wrapping. While not necessary, this will help visualizing future git diffs.
3. Migrates docs from docs.datajoint.org in a manner that mirrors the structure of datajoint-docs PR 18. While the central docs explain concepts, these submissions provide more concrete examples.
4. Temporarily changes the API page rendering to expect our current rst/sphinx docstring style, pending future updates to migrate to google style.
5. Changes CSS to reflect changes elsewhere
   • md-code-fg-color to dj-primary
   • removes 'previous'/'next' footer via md-footer

Still needs

• Updated styling following DLC #63

[kabilar]

Thanks @CBroz1! Great effort with this migration.

I did not review all the text in detail, but our team will collectively review and update over the next 1-2 months.