Added nix installation guide

README.md

@@ -2,17 +2,47 @@
 
 A TUI based [alternative](https://thealternative.ch) to [MonkeyType](https://monkeytype.com) written in rust.
 
+## Installation
+
+### Cargo
+
+Simply type
+
+```sh
+cargo install crabtype
+```
+
+### Nix
+
+To build CrabType for nix just add this derivation to your nix config
+
+```nix
+    rustapple = pkgs.callPackage (pkgs.fetchFromGitHub {
+        owner = "einsJannis";
+        repo = "CrabType";
+        rev = "<Git Revision>";
+        sha256 = "<Git SHA>";
+    }) {};
+```
+
+You can figure out the revision and the sha265 by running the application `nix-prefetch-git`
+
 ## Run
 
 ```sh
 crabtype [options...]
 ```
+
 ### Options
+
 ```
 -g|--gamemode <file>
 ```
+
 Changes the game mode to the one defined in `<file>`. This file must contain each possible text, separated by newlines.
+
 ```
 -u|--user <file>
 ```
+
 Sets the user file to `<file>`, which is the file which stores the stats in a TOML format.