[PR #8714/8690b0fb backport][3.10] Minor improvements to testing docs (#8715)

**This is a backport of PR #8714 as merged into master
(8690b0f).**

---------

Co-authored-by: Sam Bull <git@sambull.org>

Author: patchback[bot]

docs/testing.rst

@@ -32,20 +32,6 @@ insert ``pytest_plugins = 'aiohttp.pytest_plugin'`` line into
 
 
 
-Provisional Status
-~~~~~~~~~~~~~~~~~~
-
-The module is a **provisional**.
-
-*aiohttp* has a year and half period for removing deprecated API
-(:ref:`aiohttp-backward-compatibility-policy`).
-
-But for :mod:`aiohttp.test_tools` the deprecation period could be reduced.
-
-Moreover we may break *backward compatibility* without *deprecation
-period* for some very strong reason.
-
-
 The Test Client and Servers
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -76,14 +62,19 @@ Pytest
 The :data:`aiohttp_client` fixture available from pytest-aiohttp_ plugin
 allows you to create a client to make requests to test your app.
 
-A simple would be::
+To run these examples, you need to use `--asyncio-mode=auto` or add to your
+pytest config file::
+
+    asyncio_mode = auto
+
+A simple test would be::
 
     from aiohttp import web
 
     async def hello(request):
         return web.Response(text='Hello, world')
 
-    async def test_hello(aiohttp_client, loop):
+    async def test_hello(aiohttp_client):
         app = web.Application()
         app.router.add_get('/', hello)
         client = await aiohttp_client(app)