fix: Fix path in derivation

pkgs/website.nix

@@ -15,7 +15,7 @@ stdenv.mkDerivation {
   '';
 
   installPhase = ''
-    mkdir -p $out/var/www/
-    mv _site/ $out/var/www/website
+    mkdir -p $out/srv/www/
+    mv _site/ $out/srv/www/website
   '';
 }