add doc about access_token auth method

i3pystatus/github.py

@@ -7,9 +7,16 @@ from i3pystatus.core.util import user_open, internet, require
 
 class Github(IntervalModule):
     """
-    Check Github for pending notifications.
+    Check GitHub for pending notifications.
     Requires `requests`
 
+    Availables authentication methods:
+
+    * username + password
+    * access_token (manually generate a new token at https://github.com/settings/tokens)
+
+    See https://developer.github.com/v3/#authentication for more informations.
+
     Formatters:
 
     * `{unread}`        — contains the value of unread_marker when there are pending notifications
@@ -35,7 +42,7 @@ class Github(IntervalModule):
         ('unread_marker', 'sets the string that the "unread" formatter shows when there are pending notifications'),
         ("username", ""),
         ("password", ""),
-        ("access_token", ""),
+        ("access_token", "see https://developer.github.com/v3/#authentication"),
         ("color", "")
     )