Fix 306310 3.8.0 release tarball missing some files



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@12964 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/README.android b/README.android
index 138f644..d39a1da 100644
--- a/README.android
+++ b/README.android
@@ -77,6 +77,9 @@
 # different if /sdcard doesn't work on the device -- this is
 # a known cause of difficulties.
 
+# The below re-generates configure, Makefiles, ...
+# This is not needed if you start from a release tarball.
+# (in any case, the release tarball does not contain the autogen.sh file).
 ./autogen.sh
 
 # for ARM