Add vnod.

Short name for vendorimage-nodeps like snod.

Bug: 33356516
Test: works
Change-Id: Iad62aa5a021d603fa9cebe90f4e28cf09d5d49ae
diff --git a/core/help.mk b/core/help.mk
index 6e0b2c0..c034e79 100644
--- a/core/help.mk
+++ b/core/help.mk
@@ -22,6 +22,7 @@
 	@echo "droid                   Default target"
 	@echo "clean                   (aka clobber) equivalent to rm -rf out/"
 	@echo "snod                    Quickly rebuild the system image from built packages"
+	@echo "vnod                    Quickly rebuild the vendor image from built packages"
 	@echo "offline-sdk-docs        Generate the HTML for the developer SDK docs"
 	@echo "doc-comment-check-docs  Check HTML doc links & validity, without generating HTML"
 	@echo "libandroid_runtime      All the JNI framework stuff"