Issue 527: Updates another 'Additional resources' link example

Author: bredamc

supplementary_style_guide/style_guidelines/accessibility.adoc

@@ -60,7 +60,7 @@ The meaning of content relies on the order in which you present it. For example,
 
 .Additional resources
 
-*  Understanding WCAG 2.0
+*  link:https://www.w3.org/TR/UNDERSTANDING-WCAG20/Overview.html[Understanding WCAG 2.0]
 ** link:https://www.w3.org/TR/UNDERSTANDING-WCAG20/text-equiv.html[Text Alternatives]
 ** link:https://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-text-presentation.html[Images of Text]
 ** link:https://www.w3.org/TR/UNDERSTANDING-WCAG20/navigation-mechanisms-refs.html[Link Purpose (In Context)]