Add a chart of working databases to the main page [DBZ-5781]

Migrated from [DBZ-5781](https://issues.redhat.com/browse/DBZ-5781)

From Burr Sutter

bq. I would love to see a single chart on the main home page as to which databases were known to work. Ideally with a link from that database to any doc/example :-)

Start at the repository's main home page and identify where its database support information and documentation or example links are maintained. Add a single chart showing the databases known to work, with links to the relevant documentation or examples, and verify that it appears on the home page.

Written by the indexing model from the issue text.