Add a comment explaining the need to check for the escaped form of '>' when...

Add a comment explaining the need to check for the escaped form of '>' when searching for project references.

app/models/project.rb

@@ -462,6 +462,8 @@ class Project < ActiveRecord::Base
 
     # Pattern used to extract `project>` project references from text
     # (?!\w) matches any non-word character
+    # '>' or its escaped form ('&gt;') are checked for because '>' is sometimes escaped
+    # when the reference comes from an external source.
     def markdown_reference_pattern
       %r{
         #{reference_pattern}