Update ccache dir & build nix with ccache
diff --git a/src/apps/personal/nix-index.nix b/src/apps/personal/nix-index.nix
new file mode 100644
index 0000000..eab0846
--- /dev/null
+++ b/src/apps/personal/nix-index.nix
@@ -0,0 +1,3 @@
+{ pkgs, ... }: {
+    home.packages = [ pkgs.nix-index ];
+}