Add license_note

Comments not preserved during refresh.

Bug: 68860345

Test: m nothing
Change-Id: I6466d855e0125eb82f0936d9650a0831a5fb25d9
diff --git a/METADATA b/METADATA
index 6ef136d..36e572d 100644
--- a/METADATA
+++ b/METADATA
@@ -13,6 +13,7 @@
     value: "https://github.com/fonttools/fonttools/archive/4.22.0.zip"
   }
   version: "4.22.0"
+  license_note: "contains OFL fonts"
   license_type: BY_EXCEPTION_ONLY
   last_upgrade_date {
     year: 2021