Update Participating in SIG Docs and Submit a PR (#15697)

Add hyperlink to 'communicate' in Participating in SIG Docs section.
Hyperlink points to Participating in SIG Docs discussions section further down the page.

Add info to Submit a pull request bullet 5 about putting fixes #<issue_number>
or closes #<issue_number> to the PR description so GitHub will automatically close the issue

content/en/docs/contribute/start.md

@@ -40,7 +40,7 @@ Not all tasks can be done in the GitHub UI, but these are discussed in the
 
 The Kubernetes documentation is maintained by a
 {{< glossary_tooltip text="Special Interest Group" term_id="sig" >}} (SIG)
-called SIG Docs. We communicate using a Slack channel, a mailing list, and
+called SIG Docs. We [communicate](#participate-in-sig-docs-discussions) using a Slack channel, a mailing list, and
 weekly video meetings. New participants are welcome. For more information, see
 [Participating in SIG Docs](/docs/contribute/participating/).
 
@@ -247,8 +247,10 @@ pull request if it detects that you pushed a new branch to your fork.
     is the same as the commit summary, but you can change it if needed. The
     body is populated by your extended commit message (if present) and some
     template text. Read the template text and fill out the details it asks for,
-    then delete the extra template text. Leave the
-    **Allow edits from maintainers** checkbox selected. Click
+    then delete the extra template text. If you add to the description `fixes #<000000>` 
+    or `closes #<000000>`, where `#<000000>` is the number of an associated issue,
+    GitHub will automatically close the issue when the PR merges. 
+    Leave the **Allow edits from maintainers** checkbox selected. Click
     **Create pull request**.
     
     Congratulations! Your pull request is available in