When generating tags the order of endpoints wasn't taken into account.
Two endpoints with the same url prefix, for example `/api/cluster/` and
`/api/cluster/user`, have different docs and the tags is generated from
a doc of one of these two, and since the order of these endpoints might
vary it is imperative to sort them to have a deterministic output.
Signed-off-by: Pere Diaz Bou <pdiazbou@redhat.com>