Add docstrings in middlewares module.

aiogram/dispatcher/middlewares.py

@@ -5,7 +5,16 @@ log = logging.getLogger('aiogram.Middleware')
 
 
 class MiddlewareManager:
+    """
+    Middlewares manager. Works only with dispatcher.
+    """
+
     def __init__(self, dispatcher):
+        """
+        Init
+
+        :param dispatcher: instance of Dispatcher
+        """
         self.dispatcher = dispatcher
         self.loop = dispatcher.loop
         self.bot = dispatcher.bot
@@ -40,24 +49,51 @@ class MiddlewareManager:
 
 
 class BaseMiddleware:
+    """
+    Base class for middleware.
+
+    All methods on the middle always must be coroutines and name starts with "on_" like "on_process_message".
+    """
+
     def __init__(self):
         self._configured = False
         self._manager = None
 
     @property
     def manager(self) -> MiddlewareManager:
+        """
+        Instance of MiddlewareManager
+        """
         if self._manager is None:
             raise RuntimeError('Middleware is not configured!')
         return self._manager
 
     def setup(self, manager):
+        """
+        Mark middleware as configured
+
+        :param manager:
+        :return:
+        """
         self._manager = manager
         self._configured = True
 
-    def is_configured(self):
+    def is_configured(self) -> bool:
+        """
+        Check middleware is configured
+
+        :return:
+        """
         return self._configured
 
     async def trigger(self, action, args):
+        """
+        Trigger action.
+
+        :param action:
+        :param args:
+        :return:
+        """
         handler_name = f"on_{action}"
         handler = getattr(self, handler_name, None)
         if not handler: