Add license type: Apache2+MIT are NOTICE licenses

Bug: 68860345
Bug: 69058154
Bug: 151953481

Test: no code changes
Change-Id: I3dfca54d01034fe8c4e8304ed8abc49ad8dad521
diff --git a/METADATA b/METADATA
index ee6a075..6476537 100644
--- a/METADATA
+++ b/METADATA
@@ -12,5 +12,6 @@
     value: "https://github.com/bitflags/bitflags"
   }
   version: "1.2.1"
+  license_type: NOTICE
   last_upgrade_date { year: 2019 month: 12 day: 12 }
 }