Set documentation link in the Quay footer to point to docs for that specific version

Currently, the documentation link in the Quay footer points to:

https://access.redhat.com/documentation/en-us/red_hat_quay/3

Specific Quay versions should point to their own documentation, and not general docs. For instance, 3.5.x should point to 3.5 docs:

https://access.redhat.com/documentation/en-us/red_hat_quay/3.5