shell: fix typo in comment

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/1050

src/shell-global.c

@@ -1656,7 +1656,7 @@ save_variant (ShellGlobal *global,
       /* g_file_replace_contents_async() can potentially fsync() from the
        * calling thread when completing the asynchronous task. Instead, we
        * want to force that fsync() to a thread to avoid blocking the
-       * compository main loop. Using our own replace_contents_async()
+       * compositor main loop. Using our own replace_contents_async()
        * simply executes the operation synchronously from a thread.
        */
       replace_contents_async (path, bytes, cancellable, replace_variant_cb, global);