Add nix install details

Signed-off-by: 06kellyjac <jack@control-plane.io>

README.md

@@ -31,6 +31,8 @@ If you encounter an issue, please [let us know using the issue tracker](https://
 
 ## Installation
 
+**Note**: Currently, Syft is built only for Linux, macOS and Windows.
+
 ### Recommended
 ```bash
 curl -sSfL https://raw.githubusercontent.com/anchore/syft/main/install.sh | sh -s -- -b /usr/local/bin
@@ -48,7 +50,17 @@ brew tap anchore/syft
 brew install syft
 ```
 
-**Note**: Currently, Syft is built only for macOS and Linux.
+### Nix
+
+```bash
+nix-env -i syft
+```
+
+or just try it out in an ephemeral nix shell
+
+```bash
+nix-shell -p syft
+```
 
 ## Getting started