feat(README): Add tip about using Documatt Snippets for learning

Added a tip about using Documatt Snippets for practicing reStructuredText.

Signed-off-by: Josh <josh.t.richards@gmail.com>

Author: joshtrichards

README.rst

@@ -69,6 +69,12 @@ To edit a document, you can edit the .rst files on your local system, or work
 directly on GitHub. The latter is only suitable for small fixes and improvements
 because substantial editing efforts can better be controlled on your local PC.
 
+.. tip::
+   If you're getting to know our documentation syntax, `give Documatt Snippets
+   <https://snippets.documatt.com/>`_ a try. This online editor is a great way 
+   to practice with reStructuredText and Sphinx, and it provides a more accurate
+   preview of your work than GitHub does.
+
 The best way is to install a complete Sphinx build environment and work on your
 local PC. You will be able to make your own local builds, which is the fastest
 and best way to preview for errors. Sphinx will report syntax errors, missing