Add Markdown reference

Author: softforge

docs/get-started/index.md

@@ -4,6 +4,11 @@ sidebar_position: 1
 
 Get Started
 ===============
+The Joomla Developers Manual is written using Markdown language.
+A good place to start if new to Markdown is the Markdown Guide
+https://www.markdownguide.org/
+
+
 
 This is the content for the get started file
 Get Started will detail the build process, so using Git