Reorganize Flake inputs

I would prefer to follow nixpkgs-unstable for stylix, but it breaks
right now due to a mismatch in settings for a few packages. Since most
of my NixOS config is on the stable release, it's not possible to use
the master/main branch of stylix without issues like this:

danth/stylix#577

UPDATE.md

@@ -1,9 +1,9 @@
 ### How to Update to a New NixOS Version
 
 1. Update the following inputs in [flake.nix](./flake.nix) to use the new NixOS version:
-   - `nixpkgs.url`
-   - `home-manager.url`
-   - `nixvim.url`
+   - `nixpkgs`
+   - `home-manager`
+   - `stylix`
 
 2. Update state version for NixOS and Home Manager
 

flake.nix

@@ -6,16 +6,24 @@
 
     nixpkgs-unstable.url = "github:nixos/nixpkgs/nixos-unstable";
 
-    home-manager.url = "github:nix-community/home-manager/release-24.05";
-    # Ensure that nixpkgs and home-manager stay in sync
-    home-manager.inputs.nixpkgs.follows = "nixpkgs";
+    home-manager = {
+      url = "github:nix-community/home-manager/release-24.05";
+      # Ensure that nixpkgs and home-manager stay in sync
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
 
-    stylix.url = "github:danth/stylix";
+    stylix = {
+      # Follow the stable NixOS release
+      url = "github:danth/stylix/release-24.05";
+      # Use nixpkgs
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
 
     nixvim = {
-      url = "github:nix-community/nixvim/nixos-24.05";
-      # Ensure that nixpkgs and nixvim stay in sync
-      inputs.nixpkgs.follows = "nixpkgs";
+      # Follow the master/main branch
+      url = "github:nix-community/nixvim";
+      # Use nixpkgs-unstable
+      inputs.nixpkgs.follows = "nixpkgs-unstable";
     };
   };