Internal change (#184)

Add a merge notice in Centipede, pointing to a placeholder doc in FuzzTest.

Co-authored-by: Xinhao Yuan <xinhaoyuan@google.com>

centipede/USER_MIGRATION.md

diff --git a/centipede/USER_MIGRATION.md b/centipede/USER_MIGRATION.md
new file mode 100644
index 0000000..bef9c13
--- /dev/null
+++ b/centipede/USER_MIGRATION.md
@@ -0,0 +1,3 @@
+# Centipede User Migration
+
+The FuzzTest/Centipede merge is still in progress - no user actions needed yet.