Fix add/rm subcommand code highlighting

Author: rorysedgwick

book/02-git-basics/sections/recording-changes.asc

@@ -617,4 +617,4 @@ $ git add README
 
 Git figures out that it's a rename implicitly, so it doesn't matter if you rename a file that way or with the `mv` command.
 The only real difference is that `git mv` is one command instead of three -- it's a convenience function.
-More importantly, you can use any tool you like to rename a file, and address the add/rm later, before you commit.
+More importantly, you can use any tool you like to rename a file, and address the `add`/`rm` later, before you commit.