Update grouping_tasks.ipynb (#568)

grammar fix suggestion

docs/tutorials/intro/grouping_tasks.ipynb

@@ -35,7 +35,7 @@
    "source": [
     "You may have noticed that `InitNornir` got a new argument `dry_run=True`. That argument (which defaults to `False`) controls whether to apply the changes to the device or just simulate them. You can control that argument via the configuration as well. Some tasks might even allow you to override this behavior completely at the task level.\n",
     "\n",
-    "Now, let's create task that is going to group what we want to do:"
+    "Now, let's a create task that is going to group what we want to do:"
    ]
   },
   {