Automate Connection Property Docs

[sehrope]

Once #1686 is merged we'll have all the metadata for generating the connection properties docs available in a structured format (the enum values themselves). Would be good to have the connection property docs be automatically generated from those structured fields so that:

1. They're always in sync with what's actually supported.
2. Typos and updates are managed in one place.
3. We never have to remember to document new fields.

I'm not sure what the best approach for the doc generation itself but I'm adding this issue to track the overall idea of automatic doc generation.

[davecramer]

@sehrope how's this coming ? :) We have gradle now so you can do this in groovy, or kotlin or ?

[sehrope]

Hopefully some time soon. A good first step would be deleting the 9X directories: https://github.com/pgjdbc/pgjdbc/tree/master/docs/documentation