Allow PLATFORM_VERSION_CODENAME to be overridden by RELEASE_PLATFORM_VERSION_CODENAME_REL

Bug: 282843732
Test: get_build_var PLATFORM_VERSION_CODENAME
Change-Id: I16b9cf4ec8f395ceb192e35c18850fdab0a47df3
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index c107254..ce2916d 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -52,6 +52,8 @@
 
 # These are the current development codenames, if the build is not a final
 # release build.  If this is a final release build, it is simply "REL".
+# Note that this may be overridden by RELEASE_VERSION_CODENAME_REL in
+# version_util.mk.
 PLATFORM_VERSION_CODENAME.UP1A := UpsideDownCake
 PLATFORM_VERSION_CODENAME.VP1A := VanillaIceCream