Add retry loop  for fetching authentication token if any 'Internal Failure' occurs (#368)

* Add retry loop for fetching authentication token if any 'Internal failure' occurs

This is to prevent errors while client tries to connect with server and
fails with 'Internal Failure' because it was unable to fetch OAuth2
token.

* Add retry loop for fetching authentication token if any 'Internal failure' occurs

This is to prevent errors while client tries to connect with server and
fails with 'Internal Failure' because it was unable to fetch OAuth2
token.
diff --git a/docs/reference/google.oauth2.rst b/docs/reference/google.oauth2.rst
index adb9403..4f1df07 100644
--- a/docs/reference/google.oauth2.rst
+++ b/docs/reference/google.oauth2.rst
@@ -2,9 +2,9 @@
 =====================
 
 .. automodule:: google.oauth2
-    :members:
-    :inherited-members:
-    :show-inheritance:
+   :members:
+   :inherited-members:
+   :show-inheritance:
 
 Submodules
 ----------
@@ -14,4 +14,3 @@
    google.oauth2.credentials
    google.oauth2.id_token
    google.oauth2.service_account
-