Distinguish 6.5.x and 6.6.0 tools documentation

The couchbase-cli and backup repositories will not have a separate branch for release/6.6. Instead they use the mad-hatter branch for 6.5, 6.5.1, and 6.6. They use tags to distinguish between releases.

As we are using separate branches for 6.5 and 6.6 in the docs repo, we need to make sure that the release/6.6 documentation includes the the correct version of the documentation files from the couchbase-cli and backup repositories.

In particular, note that the antora.yml files for the couchbase-cli and backup repositories will specify version 6.5, whereas we will need it to specify version 6.6 for release/6.6.