Update openshift-4.md (#768)

Fixed the last code block so it is properly closed.
diff --git a/docs/openshift-4.md b/docs/openshift-4.md
index 08681c1..2e80ef1 100644
--- a/docs/openshift-4.md
+++ b/docs/openshift-4.md
@@ -119,7 +119,7 @@
 invoker:
   containerFactory:
     impl: kubernetes
-``
+```
 
 ## Limitations