Clarify that fdsan wasn't "enforcing" in its first release.

Change-Id: I02c4ff49446995b5ea33f4fa9ca30cf204307ae8
diff --git a/docs/fdsan.md b/docs/fdsan.md
index e0cf80a..6630299 100644
--- a/docs/fdsan.md
+++ b/docs/fdsan.md
@@ -3,6 +3,8 @@
 [TOC]
 
 fdsan is a file descriptor sanitizer added to Android in API level 29.
+In API level 29, fdsan warns when it finds a bug.
+In API level 30, fdsan aborts when it finds a bug.
 
 ### Background
 *What problem is fdsan trying to solve? Why should I care?*