[DOCS] Add versioning to Starlight

[melissahenderson]

Test out HiDeoo's versioning plugin, make sure everything behaves.

We don't yet know the format we'll use for versioning (eg 1.0, 2.0, etc). Need input from Max for that.

https://github.com/HiDeoo/starlight-versions
https://starlight-versions.vercel.app/getting-started/
https://starlight-versions-example.vercel.app/

[huijing]

Related to interledger/open-payments#380
Tried to use https://github.com/HiDeoo/starlight-versions as a solution, but ran into problems.
Issue tracked at: HiDeoo/starlight-versions#34