[site] Add a deprecation notice to trunk
diff --git a/README.txt b/README.txt
index 3af1b42..2374a79 100644
--- a/README.txt
+++ b/README.txt
@@ -1,3 +1,5 @@
+Note: the branch trnk is obsolete. Please use the master branch.
+
  ----
  The Apache Velocity Project
  ----