Update installers table

Author: brson

README.md

@@ -531,6 +531,14 @@ platform of your choice:
 - [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-unknown-linux-gnu](https://static.rust-lang.org/rustup/dist/i686-unknown-linux-gnu/rustup-init)
+- [mips-unknown-linux-gnu](https://static.rust-lang.org/rustup/dist/mips-unknown-linux-gnu/rustup-init)
+- [mips64-unknown-linux-gnuabi64](https://static.rust-lang.org/rustup/dist/mips64-unknown-linux-gnuabi64/rustup-init)
+- [mips64el-unknown-linux-gnuabi64](https://static.rust-lang.org/rustup/dist/mips64el-unknown-linux-gnuabi64/rustup-init)
+- [mipsel-unknown-linux-gnu](https://static.rust-lang.org/rustup/dist/mipsel-unknown-linux-gnu/rustup-init)
+- [powerpc-unknown-linux-gnu](https://static.rust-lang.org/rustup/dist/powerpc-unknown-linux-gnu/rustup-init)
+- [powerpc64-unknown-linux-gnu](https://static.rust-lang.org/rustup/dist/powerpc64-unknown-linux-gnu/rustup-init)
+- [powerpc64le-unknown-linux-gnu](https://static.rust-lang.org/rustup/dist/powerpc64le-unknown-linux-gnu/rustup-init)
+- [s390x-unknown-linux-gnu](https://static.rust-lang.org/rustup/dist/s390x-unknown-linux-gnu/rustup-init)
 - [x86_64-apple-darwin](https://static.rust-lang.org/rustup/dist/x86_64-apple-darwin/rustup-init)
 - [x86_64-linux-android](https://static.rust-lang.org/rustup/dist/x86_64-linux-android/rustup-init)
 - [x86_64-pc-windows-gnu](https://static.rust-lang.org/rustup/dist/x86_64-pc-windows-gnu/rustup-init.exe)