Add data file for additional emoji sequences

A data file with additional emoji sequences that we need to support
in Android is added.

Test: not needed
Change-Id: I53b2938594755152e20544481980a02639ba857c
diff --git a/README.android b/README.android
index 0af0512..81e2d36 100644
--- a/README.android
+++ b/README.android
@@ -16,3 +16,6 @@
 emoji-zwj-sequences.txt has been updated to Emoji 5.0 beta version, with
 sequences containing Unicode 10.0 and golfers with skin tones commented out
 (because we don't support those in our emoji font yet).
+
+An additions directory has been added for sequences that we need to support
+in addition to what's specified by Unicode.