Add link to SSG for admonitions

Author: Michael Burke

contributing_to_docs/doc_guidelines.adoc

@@ -1650,6 +1650,8 @@ Text for admonition
 ====
 ....
 
+See the link:https://redhat-documentation.github.io/supplementary-style-guide/#admonitions[Red Hat Supplementary style guide] for the valid admonition types and their definitions.
+
 [id="api-object-formatting"]
 == API object formatting