add module_path documentation, fixes #306

jedi/api_classes.py

@@ -80,6 +80,7 @@ class BaseDefinition(object):
         # generate a path to the definition
         self._module = definition.get_parent_until()
         self.module_path = self._module.path
+        """Shows the file path of a module. e.g. ``/usr/lib/python2.7/os.py``"""
 
     @property
     def start_pos(self):