added configuration documentation

README.md

@@ -4,6 +4,15 @@ Written by Wyatt J. Miller, 2026
 
 Licensed by the EPL 2.0
 
+## How to configure
+
+Change the following variables in `flake.nix` to tailor the build to your preferences:
+
+- `userName`
+- `userEmail`
+- `hostName`
+- `timeZone`
+
 ## How to build
 
 ### System