update of api docstrings across coach and tutorials [WIP] (#91)

* updating the documentation website
* adding the built docs
* update of api docstrings across coach and tutorials 0-2
* added some missing api documentation
* New Sphinx based documentation

rl_coach/exploration_policies/exploration_policy.py

@@ -31,6 +31,10 @@ class ExplorationParameters(Parameters):
 
 
 class ExplorationPolicy(object):
+    """
+    An exploration policy takes the predicted actions or action values from the agent, and selects the action to
+    actually apply to the environment using some predefined algorithm.
+    """
     def __init__(self, action_space: ActionSpace):
         """
         :param action_space: the action space used by the environment