content: fix typo in flowcontrol/2

Fixes golang/tour#575

Change-Id: Ic86fcddbd72b6a54e75b794b0b760151e2a4b78c
Reviewed-on: https://go-review.googlesource.com/128536
Reviewed-by: Andrew Bonventre <andybons@golang.org>
diff --git a/content/flowcontrol.article b/content/flowcontrol.article
index c8bcd5c..6833604 100644
--- a/content/flowcontrol.article
+++ b/content/flowcontrol.article
@@ -28,7 +28,7 @@
 
 * For continued
 
-The init and post statement are optional.
+The init and post statements are optional.
 
 .play flowcontrol/for-continued.go