Add documentation about Android 12 bug.

The wrap.<APP> property was broken in Android 12, so provide documentation
about how to workaround it.

Test: NA
Change-Id: I98fdc5801997492442802e1295fb6969f9190e1c
diff --git a/libc/malloc_debug/README.md b/libc/malloc_debug/README.md
index da26d15..662f5f8 100644
--- a/libc/malloc_debug/README.md
+++ b/libc/malloc_debug/README.md
@@ -641,6 +641,13 @@
 for the best way to use malloc debug in Android O or later on non-rooted
 devices.
 
+**NOTE**: Android 12 introduced a bug that can cause the wrap.\<APP\> property to
+no longer work. Use the commands below so that the wrap.\<APP\> instructions will work:
+
+    adb shell setprop dalvik.vm.force-java-zygote-fork-loop true
+    adb shell stop
+    adb shell start
+
 If you do have a rooted device, you can enable malloc debug for a specific
 program/application (Android O or later):