Update the experimental notice so not android p specific

This experimental notice had been Android-P specific; change the wording
to apply to more versions of Android as it is still experimental.

Bug: 131342273
Test: reading
Change-Id: I3533dc8e0281b335e80a507ef334f1cad4566a39
diff --git a/README.experimental b/README.experimental
index 27fd798..515d685 100644
--- a/README.experimental
+++ b/README.experimental
@@ -1,5 +1,5 @@
 This xaac codec (external/xaac) is experimental; it is not yet intended
 to be used on production devices.
 
-This codec should not be configured into any production Android Pie
-(Android 9) device that will be shipped.
+This codec should not be configured into any production Android device
+that is intended to be shipped.