Fix template lookup description (ansible#55557)

Previously, template lookup description was documented  as "mostly a noop".
Now,  describe that it returns template content with substituted variables.

lib/ansible/plugins/lookup/template.py

@@ -11,7 +11,7 @@
     version_added: "0.9"
     short_description: retrieve contents of file after templating with Jinja2
     description:
-      - this is mostly a noop, to be used as a with_list loop when you do not want the content transformed in any way.
+      - Returns a list of strings; for each template in the list of templates you pass in, returns a string containing the results of processing that template.
     options:
       _terms:
         description: list of files to template