:lipstick: Add semicolon to global-shortcut code example

This keeps this line consistent with the rest of the documentation.

docs/api/global-shortcut.md

@@ -16,7 +16,7 @@ app.on('ready', function() {
   // Register a 'ctrl+x' shortcut listener.
   var ret = globalShortcut.register('ctrl+x', function() {
     console.log('ctrl+x is pressed');
-  })
+  });
 
   if (!ret) {
     console.log('registration failed');