Add links to android binaries to README.md

Author: malbarbo

README.md

@@ -516,13 +516,17 @@ $ curl https://sh.rustup.rs -sSf | sh -s -- --default-toolchain nightly
 If you prefer you can directly download `rustup-init` for the
 platform of your choice:
 
+- [aarch64-linux-android](https://static.rust-lang.org/rustup/dist/aarch64-linux-android/rustup-init)
 - [aarch64-unknown-linux-gnu](https://static.rust-lang.org/rustup/dist/aarch64-unknown-linux-gnu/rustup-init)
+- [arm-linux-androideabi](https://static.rust-lang.org/rustup/dist/arm-linux-androideabi/rustup-init)
 - [arm-unknown-linux-gnueabi](https://static.rust-lang.org/rustup/dist/arm-unknown-linux-gnueabi/rustup-init)
 - [arm-unknown-linux-gnueabihf](https://static.rust-lang.org/rustup/dist/arm-unknown-linux-gnueabihf/rustup-init)
+- [armv7-linux-androideabi](https://static.rust-lang.org/rustup/dist/armv7-linux-androideabi/rustup-init)
 - [armv7-unknown-linux-gnueabihf](https://static.rust-lang.org/rustup/dist/armv7-unknown-linux-gnueabihf/rustup-init)
 - [i686-apple-darwin](https://static.rust-lang.org/rustup/dist/i686-apple-darwin/rustup-init)
 - [i686-pc-windows-gnu](https://static.rust-lang.org/rustup/dist/i686-pc-windows-gnu/rustup-init.exe)
 - [i686-pc-windows-msvc](https://static.rust-lang.org/rustup/dist/i686-pc-windows-msvc/rustup-init.exe)<sup>[†](#vs2015)</sup>
+- [i686-linux-android](https://static.rust-lang.org/rustup/dist/i686-linux-android/rustup-init)
 - [i686-unknown-linux-gnu](https://static.rust-lang.org/rustup/dist/i686-unknown-linux-gnu/rustup-init)
 - [x86_64-apple-darwin](https://static.rust-lang.org/rustup/dist/x86_64-apple-darwin/rustup-init)
 - [x86_64-pc-windows-gnu](https://static.rust-lang.org/rustup/dist/x86_64-pc-windows-gnu/rustup-init.exe)