Correct redundant phrase in About Version Control

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

Author: SherryHietala

book/01-introduction/sections/about-version-control.asc

@@ -44,7 +44,7 @@ However, this setup also has some serious downsides.
 The most obvious is the single point of failure that the centralized server represents.
 If that server goes down for an hour, then during that hour nobody can collaborate at all or save versioned changes to anything they're working on.
 If the hard disk the central database is on becomes corrupted, and proper backups haven't been kept, you lose absolutely everything -- the entire history of the project except whatever single snapshots people happen to have on their local machines.
-Local VCS systems suffer from this same problem -- whenever you have the entire history of the project in a single place, you risk losing everything.
+Local VCSs suffer from this same problem -- whenever you have the entire history of the project in a single place, you risk losing everything.
 
 ==== Distributed Version Control Systems