Add link to _GitHub basics for researchers_ article at top of README.…

…md. (#5643)

README.md

@@ -3,7 +3,7 @@
 [![Maven Central](https://img.shields.io/maven-central/v/org.broadinstitute/gatk.svg)](https://maven-badges.herokuapp.com/maven-central/org.broadinstitute/gatk)
 [![License (3-Clause BSD)](https://img.shields.io/badge/license-BSD%203--Clause-blue.svg)](https://opensource.org/licenses/BSD-3-Clause)
 
-***Please see the [GATK website](http://www.broadinstitute.org/gatk), where you can download a precompiled executable, read documentation, ask questions, and receive technical support.***
+***Please see the [GATK website](http://www.broadinstitute.org/gatk), where you can download a precompiled executable, read documentation, ask questions, and receive technical support. For GitHub basics, see [here](https://software.broadinstitute.org/gatk/documentation/article?id=23405).***
 
 ### GATK 4