Improve documentation

radicale/auth/__init__.py

@@ -53,6 +53,13 @@ def load(configuration):
 
 class BaseAuth:
     def __init__(self, configuration):
+        """Initialize BaseAuth.
+
+        ``configuration`` see ``radicale.config`` module.
+        The ``configuration`` must not change during the lifetime of
+        this object, it is kept as an internal reference.
+
+        """
         self.configuration = configuration
 
     def get_external_login(self, environ):