[PR #7916/822fbc74 backport][3.9] Add more information to contributing page (#8072)

**This is a backport of PR #7916 as merged into master
(822fbc7).**

Co-authored-by: Sam Bull <[email protected]>

Author: patchback[bot]

CHANGES/7916.doc

@@ -0,0 +1 @@
+Updated :ref:`contributing/Tests coverage <aiohttp-contributing>` section to show how we use ``codecov`` -- by :user:`Dreamsorcerer`.

CHANGES/README.rst

@@ -1,15 +1,23 @@
-.. _Adding change notes with your PRs:
+.. _Making a pull request:
+
+Making a pull request
+=====================
+
+When making a pull request, please include a short summary of the changes
+and a reference to any issue tickets that the PR is intended to solve.
+All PRs with code changes should include tests. All changes should
+include a changelog entry.
 
 Adding change notes with your PRs
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+---------------------------------
 
 It is very important to maintain a log for news of how
 updating to the new version of the software will affect
 end-users. This is why we enforce collection of the change
 fragment files in pull requests as per `Towncrier philosophy`_.
 
 The idea is that when somebody makes a change, they must record
-the bits that would affect end-users only including information
+the bits that would affect end-users, only including information
 that would be useful to them. Then, when the maintainers publish
 a new release, they'll automatically use these records to compose
 a change log for the respective version. It is important to
@@ -19,7 +27,7 @@ to the end-users most of the time. And so such details should be
 recorded in the Git history rather than a changelog.
 
 Alright! So how to add a news fragment?
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+---------------------------------------
 
 ``aiohttp`` uses `towncrier <https://pypi.org/project/towncrier/>`_
 for changelog management.
@@ -34,11 +42,14 @@ for the users to understand what it means.
 combined with others, it will be a part of the "news digest"
 telling the readers **what changed** in a specific version of
 the library *since the previous version*. You should also use
-reStructuredText syntax for highlighting code (inline or block),
+*reStructuredText* syntax for highlighting code (inline or block),
 linking parts of the docs or external sites.
-If you wish to sign your change, feel free to add ``-- by
-:user:`github-username``` at the end (replace ``github-username``
-with your own!).
+However, you do not need to reference the issue or PR numbers here
+as *towncrier* will automatically add a reference to all of the
+affected issues when rendering the news file.
+If you wish to sign your change, feel free to add
+``-- by :user:`github-username``` at the end (replace
+``github-username`` with your own!).
 
 Finally, name your file following the convention that Towncrier
 understands: it should start with the number of an issue or a
@@ -77,7 +88,7 @@ necessary to make a separate documentation fragment for documentation
 changes accompanying the relevant code changes.
 
 Examples for adding changelog entries to your Pull Requests
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+-----------------------------------------------------------
 
 File :file:`CHANGES/6045.doc.1.rst`: