Only publish GitLab pages for tags

* .gitlab-ci.yml (pages): Only publish tags.
* README.md (Documentation): Update to indicate latest release.

.gitlab-ci.yml

@@ -30,4 +30,4 @@ pages:
             - public/
         expire_in: 30 min
     only:
-        - master
+        - tags

README.md

@@ -34,10 +34,9 @@ You may then see `./configure --help` for more information.
 
 
 ## Documentation
-Compiled documentation is available [via our GitLab
+Compiled documentation for the latest release is available [via our GitLab
 mirror](https://lovullo.gitlab.io/liza/), which uses the same build pipeline
-as we do on our internal GitLab instance.  It contains the current state of
-master (with some delay), not just the most recent tag.
+as we do on our internal GitLab instance.
 
 
 ## License