Document supported database (and other) dependencies

[bri365]

Discuss adding database and other supported dependency/integration versions; we currently only document supported integrations in docs. A few ways to approach this:

1. add docs/supported_databases.md with mysql and postgres sections, and a link to it in docs/spire_server.md
2. rename docs/supported_integrations.md to docs/supported_versions.md and add a section for datastore databases
3. something else? ¯_(ツ)_/¯

[evan2645]

We discussed this during our maintainer sync today, and consensus there was that option 1 is the way to go ❤️

[github-actions]

This issue is stale because it has been open for 365 days with no activity.

[github-actions]

This issue was closed because it has been inactive for 30 days since being marked as stale.