[cloud] fix ec2_vpc_route_table module documentation - Fixes #19344 (#22367)

* improve ec2_vpc_route_table documentation

* make pep8

lib/ansible/modules/cloud/amazon/ec2_vpc_route_table.py

@@ -31,7 +31,8 @@ options:
     description:
       - "Look up route table by either tags or by route table ID. Non-unique tag lookup will fail.
         If no tags are specifed then no lookup for an existing route table is performed and a new
-        route table will be created. To change tags of a route table, you must look up by id."
+        route table will be created. To change tags of a route table or delete a route table,
+        you must look up by id."
     required: false
     default: tag
     choices: [ 'tag', 'id' ]