docs: Add automake to prerequisites

Acked-by: Jerome Forissier <jerome.forissier@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

README.md

@@ -112,12 +112,13 @@ to start with. Therefore install the following packages regardless of what
 target you will use in the end.
 
 ```bash
-$ sudo apt-get install android-tools-adb android-tools-fastboot autoconf bc \
-	bison build-essential cscope curl flex ftp-upload gdisk libattr1-dev \
-	libc6:i386 libcap-dev libfdt-dev libftdi-dev libglib2.0-dev \
-	libhidapi-dev libncurses5-dev libpixman-1-dev libstdc++6:i386 libtool \
-	libz1:i386 make mtools netcat python-crypto python-serial python-wand \
-	unzip uuid-dev xdg-utils xterm xz-utils zlib1g-dev
+$ sudo apt-get install android-tools-adb android-tools-fastboot autoconf \
+	automake bc bison build-essential cscope curl flex ftp-upload gdisk \
+	libattr1-dev libc6:i386 libcap-dev libfdt-dev libftdi-dev \
+	libglib2.0-dev libhidapi-dev libncurses5-dev libpixman-1-dev \
+	libstdc++6:i386 libtool libz1:i386 make mtools netcat python-crypto \
+	python-serial python-wand unzip uuid-dev xdg-utils xterm xz-utils \
+	zlib1g-dev
 ```
 
 ## 7.2 Install Android repo