Note on git blame in GitLab in tips lecture

tips/tips.tex

@@ -107,6 +107,9 @@
     a4394d28 (bow 2014-06 ...) Second version.
   \end{lstlisting}
   \bigskip
+  \pause
+  Similar functionality is also available in GitLab by clicking on the {\em
+    blame} button when viewing a file.
 \end{frame}