Improve documentation

Sciencentistguy · Sciencentistguy · commit de187d3864d7 · 2022-07-09T12:28:49.000+01:00
Closes #2
diff --git a/readme.md b/readme.md
@@ -4,10 +4,40 @@ Have you ever found yourself wanting to work on a rust project on NixOS without
 
 `rust-nix-shell` allows you to create a shell environment with any version of rust, à la `rustup`. You can also specify other dependencies with `-p`, à la `nix-shell`.
 
+## Note
+
+This program is intended for use on NixOS. If your system is not NixOS then I'd recommend using `rustup` instead of this --- unless you **know** that you want a nix-based rust environment, you probably don't.
+
+It produces a shell with a complete rust toolchain of the specified version (the most recent stable, by default). This is useful when you're working on a project that does not have nix development files in the repo, or if they are not compatible with a nix-based rust-analyzer installation.
+
 ## Dependencies
 
 This program shells out to `nix-shell`, finding it from `$PATH`. It also by default calls `zsh` from `$PATH`, but this is configurable
 
+## Installation
+
+This repository is a flake, providing the output `rust-nix-shell`, and contains a `default.nix` for backwards compatibility.
+
+The recommended way of installing this is by adding it to your system configuration. (For an example, look at my [system flake](https://github.com/Sciencentistguy/nixfiles))
+
+Failing that, it can be run ephemerally with `nix run`:
+
+```sh
+nix run 'github:Sciencentistguy/rust-nix-shell' -- [rust-nix-shell arguments]
+```
+
+Or, it can be installed using `nix profile`:
+
+```sh
+nix profile install 'github:Sciencentistguy/rust-nix-shell'
+```
+
+For backwards compatibility, a `default.nix` is provided, allowing `rust-nix-shell` to be installed using `nix-env`:
+
+```sh
+nix-env --dry-run -f 'https://github.com/Sciencentistguy/rust-nix-shell/archive/master.tar.gz' -i rust-nix-shell
+```
+
 ## Usage
 
 `rust-nix-shell --help`
