Update content-markup-reference.md (#31677)

Author: streats

contributing/content-markup-reference.md

@@ -73,7 +73,7 @@ To render syntax highlighting in command line instructions, we use triple backti
 
 This syntax highlighting renders light text on a dark background, and should be reserved for command line instructions.
 
-Within the command-line syntax, use all uppercase text to indicate content that varies for each user, such as a user or repository name.
+Within the command-line syntax, use all uppercase text to indicate placeholder text or content that varies for each user, such as a user or repository name.
 
 **Copy-able code blocks**