Fix 'laster' to 'later' typo in README.md

Change-Id: Id610ccdf3a1f87fa6089459f5c597ec5b74c65c7

README.md

diff --git a/README.md b/README.md
index 781ed57..ae1184d 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,7 @@
 Events can be anything, from the traditional stream events
 to the Gerrit metrics.
 
-This plugin requires Gerrit 2.13 or laster.
+This plugin requires Gerrit 2.13 or later.
 
 Environments
 ---------------------