update nix-related documentation

Author: bohendo

CONTRIBUTING.md

@@ -87,6 +87,16 @@ To run
 
 - Ensure JSON keys are `camelCase` rather than `snake_case`, where possible.
 
+### Nix considerations
+
+- If any dependencies are added or removed, the `vendorHash` property in ./flake.nix will need to be updated. To do so, run `nix build`. If it works, you're good to go. If a change is required, you'll see an error that looks like the following. Replace the `specified` value of `vendorHash` in the medusa package of flake.nix with what nix actually `got`.
+
+```
+error: hash mismatch in fixed-output derivation '/nix/store/sfgmkr563pzyxzllpmwxdbdxgrav8y1p-medusa-0.1.8-go-modules.drv':
+         specified: sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=
+            got:    sha256-12Xkg5dzA83HQ2gMngXoLgu1c9KGSL6ly5Qz/o8U++8=
+```
+
 ## License
 
 The license for this software can be found [here](./LICENSE).

README.md

@@ -44,7 +44,7 @@ The master branch can be installed using the following command:
 brew install --HEAD medusa
 ```
 
-For more information on building from source or obtaining binaries for Windows and Linux, please refer to the [installation guide](./docs/src/getting_started/installation.md).
+For more information on building from source, using nix, or obtaining binaries for Windows and Linux, please refer to the [installation guide](./docs/src/getting_started/installation.md).
 
 ## Contributing
 

docs/src/getting_started/installation.md

@@ -22,6 +22,27 @@ Run the following command to install `medusa`:
 brew install medusa
 ```
 
+## Installing with Nix
+
+### Prerequisites
+
+Make sure nix is installed and that `nix-command` and `flake` features are enabled. The [Determinate Systems nix-installer](https://determinate.systems/nix-installer/) will automatically enable these features and is the recommended approach. If nix is already installed without these features enabled, run the following commands.
+
+```
+mkdir -p ~/.config/nix
+echo 'experimental-features = nix-command flakes' > ~/.config/nix/nix.conf
+```
+
+### Build `medusa`
+
+`nix build` will build medusa and wire up independent copies of required dependencies. The resulting binary can be found at `./result/bin/medusa`
+
+### Install `medusa`
+
+After building, you can add the build result to your PATH using nix profiles by running the following command:
+
+`nix profile install ./result`
+
 ## Building from source
 
 ### Prerequisites