Improve Gunicorn logging documentation (aio-libs#2921)

* Improve gunicorn logging documentation

* Fix spelling error in logging documentation

* Fix anchor linking between different files

* Create 2921.doc

CHANGES/2921.doc

@@ -0,0 +1 @@
+Improve Gunicorn logging documentation

docs/deployment.rst

@@ -280,6 +280,8 @@ In this case, we will use:
   many worker processes to use for handling requests. (See the
   documentation for recommendations on `How Many Workers?
   <http://docs.gunicorn.org/en/latest/design.html#how-many-workers>`_)
+* you may also want to use the *'--accesslog'* flag to enable the access
+  log to be populated. (See :ref:`logging <gunicorn-accesslog>` for more information.)
 
 The custom worker subclass is defined in ``aiohttp.GunicornWebWorker``::
 

docs/logging.rst

@@ -102,14 +102,26 @@ Example of drop-in replacement for :class:`aiohttp.helpers.AccessLogger`::
                            f'"{request.method} {request.path} '
                            f'done in {time}s: {response.status}')
 
-.. note::
 
-   When `Gunicorn <http://docs.gunicorn.org/en/latest/index.html>`_ is used for
-   :ref:`deployment <aiohttp-deployment-gunicorn>` its default access log format
-   will be automatically replaced with the default aiohttp's access log format.
+.. _gunicorn-accesslog:
+
+Gunicorn access logs
+^^^^^^^^^^^^^^^^^^^^
+When `Gunicorn <http://docs.gunicorn.org/en/latest/index.html>`_ is used for
+:ref:`deployment <aiohttp-deployment-gunicorn>` its default access log format
+will be automatically replaced with the default aiohttp's access log format.
+
+If Gunicorn's option access_logformat_ is
+specified explicitly it should use aiohttp's format specification.
+
+Gunicorn access log works only if accesslog_ is specified explicitly in your
+config or as a command line option.
+This configuration can be either a path or ``'-'``. If the application uses
+a custom logging setup intercepting the ``'gunicorn.access'`` logger,
+accesslog_ should be set to ``'-'`` to prevent Gunicorn to create an empty
+access log file upon every startup.
+
 
-   If Gunicorn's option access_logformat_ is
-   specified explicitly it should use aiohttp's format specification.
 
 
 Error logs
@@ -127,3 +139,6 @@ To use different logger name please specify *logger* parameter
 
 .. _access_logformat:
     http://docs.gunicorn.org/en/stable/settings.html#access-log-format
+
+.. _accesslog:
+    http://docs.gunicorn.org/en/stable/settings.html#accesslog