[docs][minor] Variables user guide: fix grammar (#39427)

docs/docsite/rst/user_guide/playbooks_variables.rst

@@ -601,7 +601,7 @@ While it's mentioned elsewhere in that document too, here's a quick syntax examp
 Registered variables are valid on the host the remainder of the playbook run, which is the same as the lifetime of "facts"
 in Ansible.  Effectively registered variables are just like facts.
 
-When using ``register`` with a loop the data structure placed in the variable during a loop, will contain a ``results`` attribute, that is a list of all responses from the module. For a more in-depth example of how this works, see the :doc:`playbooks_loops` section on using register with a loop.
+When using ``register`` with a loop, the data structure placed in the variable during the loop will contain a ``results`` attribute, that is a list of all responses from the module. For a more in-depth example of how this works, see the :doc:`playbooks_loops` section on using register with a loop.
 
 .. note:: If a task fails or is skipped, the variable still is registered with a failure or skipped status, the only way to avoid registering a variable is using tags.