document where gitlab pages logs are and the latest gitlab pages issue

howto/gitlab.md

@@ -486,6 +486,25 @@ This command also shows general info about the GitLab instance:
 
 it is especially useful to find on-disk files and package versions.
 
+### GitLab pages not found
+
+If you're looking for a way to track GitLab pages error, know that the
+webserver logs are in `/var/log/nginx/gitlab_pages_access`, but that
+only proxies requests for the GitLab Pages engine, which (JSON!) logs
+live in `/var/log/gitlab/gitlab-pages/current`.
+
+If you get a `"error":"domain does not exist"` problem, make sure the
+entire *pipeline* actually succeeds. Typically, the "pages:deploy" job
+can fail with:
+
+    Artifacts for pages are too large
+
+In that case, you need to go into the Admin Area -> Settings ->
+Preferences -> Pages and bump the size limit. It defaults to 100MB and
+we bumped it to 1024MB at the time of writing. Note that GitLab CI/CD
+also have a similar setting which might (or might not?) affect such
+problems.
+
 ## Disaster recovery
 
 In case the entire GitLab machine is destroyed, a new server should be