Delete manual installation URLs

These have existed since the beginning of time, but they haven't needed to exist
since long before 1.0. Let's just delete them now that they're out of date
anyway.

README.md

@@ -11,22 +11,6 @@ Learn more at http://doc.crates.io/
 Cargo is distributed by default with Rust, so if you've got `rustc` installed
 locally you probably also have `cargo` installed locally.
 
-If, however, you would like to install Cargo from the nightly binaries that are
-generated, you may also do so! Note that these nightlies are not official
-binaries, so they are only provided in one format with one installation method.
-Each tarball below contains a top-level `install.sh` script to install Cargo.
-
-* [`x86_64-unknown-linux-gnu`](https://static.rust-lang.org/cargo-dist/cargo-nightly-x86_64-unknown-linux-gnu.tar.gz)
-* [`i686-unknown-linux-gnu`](https://static.rust-lang.org/cargo-dist/cargo-nightly-i686-unknown-linux-gnu.tar.gz)
-* [`x86_64-apple-darwin`](https://static.rust-lang.org/cargo-dist/cargo-nightly-x86_64-apple-darwin.tar.gz)
-* [`i686-apple-darwin`](https://static.rust-lang.org/cargo-dist/cargo-nightly-i686-apple-darwin.tar.gz)
-* [`x86_64-pc-windows-gnu`](https://static.rust-lang.org/cargo-dist/cargo-nightly-x86_64-pc-windows-gnu.tar.gz)
-* [`i686-pc-windows-gnu`](https://static.rust-lang.org/cargo-dist/cargo-nightly-i686-pc-windows-gnu.tar.gz)
-* [`x86_64-pc-windows-msvc`](https://static.rust-lang.org/cargo-dist/cargo-nightly-x86_64-pc-windows-msvc.tar.gz)
-
-Note that if you're on Windows you will have to run the `install.sh` script from
-inside an MSYS shell, likely from a MinGW-64 installation.
-
 ## Compiling from Source
 
 Cargo requires the following tools and packages to build: