NO-JIRA add supporting link for commit msg

docs/hacking-guide/en/code.md

@@ -75,7 +75,8 @@ related JIRA or an email to the [dev list](http://activemq.apache.org/mailing-li
          $ git commit
 
    <a name="commitMessageDetails"></a> When you commit your changes you will need to supply a commit message. We follow the
-    50/72 git commit message format. An ActiveMQ Artemis commit message should be formatted in the following manner:
+    50/72 git commit message format as recommended in the [official Git book](https://git-scm.com/book/en/v2/Distributed-Git-Contributing-to-a-Project).
+    An ActiveMQ Artemis commit message should be formatted in the following manner:
     
    1. Add the first line with the summary, using maximum 50 characters. Start the summary with the jira key (ARTEMIS-XXX)
       followed by a brief description of the change. Use the prefix `NO-JIRA` only for a very small insignificant change,
@@ -168,4 +169,4 @@ To keep track of all licenses in ActiveMQ Artemis, new dependencies must be adde
 added under the dependency management section with version and labelled with a comment highlighting the license for the
 dependency version.  See existing dependencies in the main pom.xml for examples.  The dependency can then be added to
 individual ActiveMQ Artemis modules *without* the version specified (the version is implied from the dependency management
-section of the top level pom).  This allows ActiveMQ Artemis developers to keep track of all dependencies and licenses.
+section of the top level pom).  This allows ActiveMQ Artemis developers to keep track of all dependencies and licenses.