Update documentation of overlay

This was moved from vendor/ so the documentation is out of date.

Change-Id: Ia03065ed75c01dfb2d106a7c3f684ed59e02e77c
diff --git a/overlay/packages/apps/CarrierConfig/res/xml/vendor.xml b/overlay/packages/apps/CarrierConfig/res/xml/vendor.xml
index 9c2c243..384422b 100644
--- a/overlay/packages/apps/CarrierConfig/res/xml/vendor.xml
+++ b/overlay/packages/apps/CarrierConfig/res/xml/vendor.xml
@@ -1,5 +1,5 @@
 <?xml version='1.0' encoding='utf-8' standalone='yes' ?>
-<!-- This is a place for vendor-specific config values. The format and
+<!-- This is a place for device-specific config values. The format and
      filtering rules are the same as those in carrier_config*.xml files. This
      file is read after any specific config file from the assets folder, so it
      must use explicit filters for MCC ad MNC if that is desired. -->