[docs] update database CA split release versions

[GavinFrazar]

This PR updates the Teleport versions that added the db CA split, which was backported to v13 and v14.
I added version variables in config.json to make it easy to refer to the correct versions consistently.

We already have a v13 release with the CA split, I'm just leaving this in draft until we get a v14 patch release that has the CA split in it as well.
Update: patch was released in 14.3.7

[github-actions]

🤖 Vercel preview here: https://docs-jzpcsjfkw-goteleport.vercel.app/docs/ver/preview

[github-actions]

🤖 Vercel preview here: https://docs-nt107ulnw-goteleport.vercel.app/docs/ver/preview

[greedy52]

Thanks for updating the versions. A customer on support the other day asked why downgrading Teleport breaks things (in his case, it's caused by the new role version). Maybe worth adding a note somewhere that if downgrading Teleport after the CA split, make sure the downgraded version (regardless of major or minor or patch) also requires the CA split or they may have to reconfigure the databases.

[GavinFrazar]

Thanks for updating the versions. A customer on support the other day asked why downgrading Teleport breaks things (in his case, it's caused by the new role version). Maybe worth adding a note somewhere that if downgrading Teleport after the CA split, make sure the downgraded version (regardless of major or minor or patch) also requires the CA split or they may have to reconfigure the databases.

sounds good, I can add that to the migration guide since it only breaks if they rotate their CAs before downgrading.
In the middle of a bunch of terraform stuff, but I'll make that docs update tomorrow

[github-actions]

🤖 Vercel preview here: https://docs-9ox7nb8c8-goteleport.vercel.app/docs/ver/preview

[public-teleport-github-review-bot]

@GavinFrazar See the table below for backport results.

Branch	Result
branch/v13	Create PR
branch/v14	Create PR
branch/v15	Create PR