Add package documentation for support transition

Change-Id: I132e0a847313eda07958aa65e735f95587b33cd4
diff --git a/transition/src/android/support/transition/package.html b/transition/src/android/support/transition/package.html
new file mode 100644
index 0000000..b09005f
--- /dev/null
+++ b/transition/src/android/support/transition/package.html
@@ -0,0 +1,8 @@
+<body>
+
+Support android.transition classes to provide transition API back to android API level 14.
+This library contains {@link android.support.transition.Transition},
+{@link android.support.transition.TransitionManager}, and other related classes
+back-ported from their platform versions introduced Android API level 19.
+
+</body>