doc: adding content in Create a PR section (#468)

* doc: adding content in `Create a PR` section

* Apply suggestions from code review

Co-authored-by: Roberto Pastor Muela <[email protected]>

* Apply suggestions from code review

Co-authored-by: Roberto Pastor Muela <[email protected]>

---------

Co-authored-by: Roberto Pastor Muela <[email protected]>

Author: clatapie

doc/source/content-writing/_static/assigning_yourself_PR.png

@@ -295,6 +295,12 @@ To create a PR:
 #. Click **Compare & pull request**.
    The **Open a pull request** window opens.
 #. Supply a commit message and an optional extended description.
+#. Assign the PR to yourself by clicking **assign yourself** on the right side of the window.
+
+   .. image:: ../_static/assigning_yourself_PR.png
+      :alt: Assign yourself to the PR
+
+#. If the PR is meant to fix an issue, add **Closes #issue_number** to the PR description.
 #. Click **Create pull request**. Or, if you want to create a draft pull request,
    use the dropdown to select **Create draft pull request**.