Remove empty docstring in filter plugin (#106)

A recent change somewhere upstream broke the sanity tests. This
partially reverts 0eb1559cc7 to remove the
empty docstring on the filter plugin. The reason the empty docstring was
added in the first place was to fix a problem with the doc generation
script. However, a recent change to the collection_prep project fixed
that issue so we no longer need the empty docstring.

plugins/filter/k8s.py

@@ -22,9 +22,6 @@ def k8s_config_resource_name(resource):
 
 # ---- Ansible filters ----
 class FilterModule(object):
-    """
-
-    """
 
     def filters(self):
         return {