Change deb installation from crates.io to git

There have been a number of issues an PRs opened since
the cargo-deb installation does not work with the latest
version from crates.io.

To help out users until the crates.io version is updated,
the installation instructions have been temporarily
changed to install `cargo-deb` through github.

README.md

@@ -56,7 +56,7 @@ Using `cargo deb`, you can create and install a deb file.
 ```sh
 git clone https://github.com/jwilm/alacritty.git
 cd alacritty
-cargo install cargo-deb
+cargo install --git https://github.com/mmstick/cargo-deb cargo-deb
 cargo deb --install
 ```