gh-101100: Fix sphinx warnings in library/asyncio-dev.rst (GH-111179)

* gh-101100: Fix sphinx warnings in `library/asyncio-dev.rst`

* Update Doc/library/asyncio-eventloop.rst

* Update Doc/library/asyncio-eventloop.rst

---------

Co-authored-by: Carol Willing <[email protected]>

Author: sobolevn

Doc/library/asyncio-eventloop.rst

@@ -243,9 +243,9 @@ Scheduling callbacks
    See the :ref:`concurrency and multithreading <asyncio-multithreading>`
    section of the documentation.
 
-.. versionchanged:: 3.7
-   The *context* keyword-only parameter was added. See :pep:`567`
-   for more details.
+   .. versionchanged:: 3.7
+      The *context* keyword-only parameter was added. See :pep:`567`
+      for more details.
 
 .. _asyncio-pass-keywords:
 
@@ -1391,6 +1391,14 @@ Enabling debug mode
       The new :ref:`Python Development Mode <devmode>` can now also be used
       to enable the debug mode.
 
+.. attribute:: loop.slow_callback_duration
+
+   This attribute can be used to set the
+   minimum execution duration in seconds that is considered "slow".
+   When debug mode is enabled, "slow" callbacks are logged.
+
+   Default value is 100 milliseconds.
+
 .. seealso::
 
    The :ref:`debug mode of asyncio <asyncio-debug-mode>`.

Doc/tools/.nitignore

@@ -30,7 +30,6 @@ Doc/howto/logging.rst
 Doc/howto/urllib2.rst
 Doc/library/abc.rst
 Doc/library/ast.rst
-Doc/library/asyncio-dev.rst
 Doc/library/asyncio-eventloop.rst
 Doc/library/asyncio-extending.rst
 Doc/library/asyncio-policy.rst