docs: update readme, deindent package variant example

Author: kittywitch

README.md

@@ -21,8 +21,8 @@ CI_PLATFORM=impure nix run -f https://github.com/arcnmx/ci/archive/v0.7.tar.gz r
 
 package.nix supports a `features` parameter. If you define a package with features, you can use the variant in both the outputs and within CI to provide builds with certain features.
 ```nix
-        exampleWithFeatures = pkgs.callPackage ./package.nix {
-          craneLib = packageCraneLib;
-          features = [ "lots-of-spaghetti" ];
-        };
+exampleWithFeatures = pkgs.callPackage ./package.nix {
+  craneLib = packageCraneLib;
+  features = [ "lots-of-spaghetti" ];
+};
 ```