move registry from main to latest published tag

[Kira-Pilot]

As part of coder/modules#301, we need to move registry.coder.com/modules from main to the latest published tag. Otherwise, users will see unpublished versions in the registry.

Going forward, we also want to support separate versioning for each module so that we can follow semantic versioning practices, but for now this should be an easy workaround.

[matifali]

This will have the drawback of not allowing minor doc changes (e.g., typos, screenshots etc.) without pushing a new version.

[bcpeinhardt]

How we implement this will be heavily dependent on how we architect the new registry.