Replace android-tools-adb by adb

Here is the description of the adb package in Debian:

> Description: Android Debug Bridge
>
> A versatile command line tool that lets you communicate with an
> emulator instance or connected Android-powered device.
>
> This package recommends "android-sdk-platform-tools-common" which
> contains the udev rules for Android devices. Without this package, adb
> and fastboot need to be running with root permission.

And android-tools-adb:

> Description: transitional package
>
> This is a transitional package. It can safely be removed.

BUILD.md

@@ -12,7 +12,7 @@ case, use the [prebuilt server] (so you will not need Java or the Android SDK).
 ## Requirements
 
 You need [adb]. It is available in the [Android SDK platform
-tools][platform-tools], or packaged in your distribution (`android-tools-adb`).
+tools][platform-tools], or packaged in your distribution (`adb`).
 
 On Windows, download the [platform-tools][platform-tools-windows] and extract
 the following files to a directory accessible from your `PATH`: