Fix a typo in checkout example

Author: MarkEWaite

src/main/resources/hudson/plugins/git/GitSCM/help.html

@@ -125,7 +125,7 @@
 <pre>
 checkout poll: false,
          scmGit(userRemoteConfigs: [
-                    [ url: 'git://git.kernel.org/pub/scm/git/git.git ]
+                    [ url: 'git://git.kernel.org/pub/scm/git/git.git' ]
                 ])
 </pre>
     </p>