Fix typo on readme

Change-Id: I80bf3656d08bdf0f485edb33c7bd5013733209d7
diff --git a/README.md b/README.md
index 3d91143..63fe80d 100644
--- a/README.md
+++ b/README.md
@@ -136,8 +136,7 @@
 
 To contribute to ONOS, please refer to [Sample Gerrit
 Workflow](https://wiki.onosproject.org/display/ONOS/Sample+Gerrit+Workflow). It
-should includes most of the things you'll need to get your contribution started!
-
+should include most of the things you'll need to get your contribution started!
 
 ## More information