Fix additional Markdown line lengths for Codacy compliance

- Break long prose lines to under 120 characters
- Improve readability of documentation
- URLs and ASCII art diagrams left unchanged (cannot be shortened)

.wiki/Testing-Framework.md

@@ -1,6 +1,8 @@
 # WordPress Plugin Testing Framework
 
-This document outlines how to set up and run tests for our plugin in both single site and multisite WordPress environments.
+This document outlines how to set up and run tests for our plugin.
+
+It covers both single site and multisite WordPress environments.
 
 ## Overview