add in how to fast forward

Author: schacon

book/03-git-branching/sections/rebasing.asc

@@ -39,6 +39,12 @@ image::images/basic-rebase-3.png[Rebasing the change introduced in `C3` onto `C4
 
 At this point, you can go back to the master branch and do a fast-forward merge.
 
+[source,console]
+----
+$ git checkout master
+$ git merge experiment
+----
+
 .Fast-forwarding the master branch
 image::images/basic-rebase-4.png[Fast-forwarding the master branch.]