Correct redundant phrase in Recording Changes to the Repository

"VCS systems" is a redundant acronym phrase (like "ATM machines").

Author: SherryHietala

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

@@ -579,7 +579,7 @@ This command removes all files whose names end with a `~`.
 ==== Moving Files
 
 (((files, moving)))
-Unlike many other VCS systems, Git doesn't explicitly track file movement.
+Unlike many other VCSs, Git doesn't explicitly track file movement.
 If you rename a file in Git, no metadata is stored in Git that tells it you renamed the file.
 However, Git is pretty smart about figuring that out after the fact -- we'll deal with detecting file movement a bit later.