PRR fix

Author: Chris Cho

source/style-guide/markup/directives/sharedinclude.txt

@@ -20,7 +20,7 @@ Sourcing file
   directive to pull content from an external file.
 
 Placeholder
-  A variable that identifies where replacement content should be inserted.
+  Variable that identifies where replacement content should be inserted.
   These variables are represented as a name surrounded by the ``|`` (pipe)
   character. Add them in the external file and define the replacement content
   in the sourcing file.