README: Add a brief 'script-extractor' tool description

Fixes https://github.com/linux-sunxi/sunxi-tools/pull/32

Signed-off-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>

README

@@ -63,5 +63,9 @@ meminfo:
 	get a toolchain, and run:
 		make CROSS_COMPILE=arm-linux-gnueabihf- meminfo
 
+script-extractor:
+	A simple tool, which can be executed on a rooted Android device
+	to dump the script.bin blob from RAM via reading /dev/mem.
+
 This software is licensed under the terms of GPLv2+ as defined by the
 Free Software Foundation, details can be read in the COPYING file.