More class based handlers

docs/dispatcher/class_based_handlers/callback_query.md

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+# CallbackQueryHandler
+
+There is base class for callback query handlers.
+
+## Simple usage:
+```pyhton3
+from aiogram.handlers import CallbackQueryHandler
+
+...
+
+@router.callback_query_handler()
+class MyHandler(CallbackQueryHandler):
+    async def handle(self) -> Any: ...
+
+```
+
+## Extension
+
+This base handler is subclass of [BaseHandler](basics.md#basehandler) with some extensions:
+
+- `self.from_user` is alias for `self.event.from_user`
+- `self.message` is alias for `self.event.message`
+- `self.callback_data` is alias for `self.event.data`
+
+## Related pages
+
+- [BaseHandler](basics.md#basehandler)
+- [CallbackQuery](../../api/types/callback_query.md)
+- [Router.callback_query_handler](../router.md#callback-query)