insist on canonical git URLs

tsa/howto/gitlab.mdwn

@@ -82,11 +82,17 @@ stuff.
 
 ### Not migrated
 
-We are *not* migrating away from Gitolite and Jenkins just yet. Those
-services are still operational and still the reference services for
-source code hosting and continuous integration. Those services *might*
-eventually be migrated to GitLab, but that's part of a future
-migration plan.
+We are *not* migrating away from Gitolite and Jenkins just yet. This
+means those services are still fully operational and their equivalent
+features in GitLab are *not* supported (namely Git hosting and
+CI). Those services *might* eventually be migrated to GitLab, but
+that's not part of the current migration plan.
+
+Again, the canonical copy for source code hosted by git is:
+
+ * `git-rw.torproject` - writable git repositories over SSH
+ * <https://git.torproject.org/> - readonly clones
+ * <https://gitweb.torproject.org/> - web interface
 
 We also do not host "GitLab pages", the static site hosting provided
 by GitLab.