added index.php again in documentation/release

Change-Id: I10e8abcc5c3577080f2bee442296e1a4ab83e9e8
diff --git a/documentation/release/index.php b/documentation/release/index.php
new file mode 100644
index 0000000..c967886
--- /dev/null
+++ b/documentation/release/index.php
@@ -0,0 +1,6 @@
+<?php
+header("HTTP/1.1 303 See other");
+header("Location: introduction.html");
+exit();
+?>
+