Update docs to match Plone documentation standards

[gforcada]

We have docs thanks to @jensens ❤️ but they need some work to match Plone documentation standards, as @stevepiercy mentioned on #332 .

Let's get the shortcomings of the current docs so we can keep improving them until they can be part of docs.plone.org, where they belong 👍🏾

[stevepiercy]

For general guidance, see Contribute to documentation.

See also these two sections for incorporation into 6.docs.plone.org.

• Importing external docs and converting to MyST
• Importing external docs with submodules

If you find anything in those guides that is useful or needs improvement, please let me know. Thank you!