Update playbooks_loops.rst (#38440) (#38475)

Missing parentheses
+label: docsite_pr

(cherry picked from commit 061ecac3b5)

docs/docsite/rst/user_guide/playbooks_loops.rst

@@ -209,12 +209,12 @@ There is also a specific lookup plugin ``inventory_hostnames`` that can be used
     # show all the hosts in the inventory
     - debug:
         msg: "{{ item }}"
-      loop: "{{lookup('inventory_hostnames', 'all'}}"
+      loop: "{{ lookup('inventory_hostnames', 'all') }}"
 
     # show all the hosts matching the pattern, ie all but the group www
     - debug:
         msg: "{{ item }}"
-      loop: "{{lookup('inventory_hostnames', 'all!www'}}"
+      loop: "{{ lookup('inventory_hostnames', 'all!www') }}"
 
 More information on the patterns can be found on :doc:`intro_patterns`