Fix 'Module index' broken HTTP link

'Module Index' link points to HTML doc generated from source/api
RST files. These RST files are generated by pbr, by setting the
parameter 'autodoc_index_modules' to True.

Partial-Bug: #1535244
Change-Id: Ifceb5a140599d3968ea3d353b12c0bbe99d955e6

watcher/decision_engine/solution/base.py

@@ -92,13 +92,13 @@ class BaseSolution(object):
         """Add a new Action in the Action Plan
 
         :param action_type: the unique id of an action type defined in
-        entry point 'watcher_actions'
+            entry point 'watcher_actions'
         :param applies_to: the unique id of the resource to which the
-        `Action` applies.
+            `Action` applies.
         :param input_parameters: An array of input parameters provided as
-         key-value pairs of strings.
-         Each key-pair contains names and values that match what was previously
-         defined in the `Action` type schema.
+            key-value pairs of strings. Each key-pair contains names and
+            values that match what was previously defined in the `Action`
+            type schema.
         """
         raise NotImplementedError()