documented base async middleware

Author: amirreza8002

README.md

@@ -22,6 +22,7 @@ these tools are provided for now:
 2. async generic class based views.
 3. async paginator
 4. async auth mixins 
+5. async base middleware
 
 more to come...
 

docs/index.md

@@ -11,6 +11,7 @@ check out the [installation](installation.md) guide for how to get this package.
 * async generic class based views.
 * async auth mixins.
 * async paginator.
+* async base middleware
 * more to come...
 
 ## Rational

docs/middleware/base.md

@@ -0,0 +1,23 @@
+## AsyncMiddlewareMixin
+
+a base class to create async only middlewares.
+
+it is very similar to django's [MiddlewareMixin](https://docs.djangoproject.com/en/5.1/topics/http/middleware/#upgrading-pre-django-1-10-style-middleware)
+with the following specification:
+
+`__call__` method is async, so you need to `await` the middleware instance.
+```pycon
+>>> middleware = AsyncMiddlewareMixin(get_response)
+>>> await middleware()
+```
+where `get_response` is an async function, sync functions are not supported and will raise an error.
+
+----------------------------
+
+other methods are as follows:
+
+* `process_request` and `process_response` are `await`ed inside the middleware and have to be async
+
+* `process_view` and `process_template_response` can be either sync or async, but **async is preferred**, if it's sync django will wrap it as async which might have slight performance reduction.
+
+* `process_exception` can be either sync or async, but **sync is preferred**, if async is used django wraps the method to be called synchronously.