doc: fix submittingpatches.md

Fixed H2 title in 2nd section
Rephrased the 1st section to remove duplicate content.

Signed-off-by: Francesco Servidio <francesco.servidio@nordicsemi.no>

docs/SubmittingPatches.md

@@ -1,33 +1,38 @@
-# Submitting patches
+# Patch submission
 
-Development on MCUboot primarily takes place in github, at:
-https://github.com/mcu-tools/mcuboot
+The development of MCUboot takes place in the [MCUboot GitHub
+repository](https://github.com/mcu-tools/mcuboot).
 
-Changes should be submitted via github pull requests.  Each commit
-should have a Signed-off-by line for the author (and the committer, if
-that is different).  It is not necessary (or possible) to get a
-Signed-off-by from Github itself, even though some commits may be
-generated by that tool.
+To submit patches, use GitHub pull requests.
 
-The Signed-off-by line should be at the end of the commit text, in the
-last blank-line-separated section.  There can be multiple lines in
-this section (the format being roughly like RFC-2822).  Currently
-supported trailer lines are:
+Each commit has to have, in the commit message, a "Signed-off-by" line
+that mentions the author (and the committer, if that is different). You
+must add this line at the end of the commit text, separated by a blank
+line. You can also add a line linking the commit to a specific GitHub
+issue, as this section supports multiple lines, similarly to RFC-2822.
 
-    Signed-off-by: Developer Name <devname@example.com>
+The supported trailer lines are structured as follows:
 
-which indicates that the signer agrees to the Developer Certificate of
-Origin below, and
+- A line that indicates that the signer agrees to the "Developer
+Certificate of Origin" located at the bottom of this page:
 
-    JIRA: MCUB-1234
+  ```
+      Signed-off-by: Developer Name <devname@example.com>
+  ```
 
-which associates this commit with a particular JIRA ticket.  You can
-put more than one JIRA ticket, by separating them with a comma and a
-space.  JIRA is quite flexible about where the indicators go, but
-putting them in a trailer with a common format will make them easier
-to find later.
+- A line that links this commit to specific GitHub issues, if present:
 
-# Developer certificate of origin
+  ```
+  Keyword #GH_issue_number
+  ```
+
+  For more details about linking a GitHub pull request to a GitHub issue,
+  see this [link]
+  (https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue).
+
+## Developer certificate of origin
+
+The following is the "Developer Certificate of Origin":
 
 ```
 Developer Certificate of Origin