Add flake outputs for the manuals

flake.nix

@@ -6,20 +6,30 @@
   description = "A collection of packages for the Nix package manager";
 
   outputs = inputs:
-    let pkgs = import ./. { system = "x86_64-linux"; }; in
+    let
+      pkgs = import ./. { system = "x86_64-linux"; };
+      jobs = import ./pkgs/top-level/release.nix {
+        nixpkgs = inputs.self;
+      };
+    in
     {
       lib = (import ./lib) // {
         nixosSystem = import ./nixos/lib/eval-config.nix;
       };
 
-      checks.tarball = (import ./pkgs/top-level/release.nix {
-        nixpkgs = inputs.self;
-      }).tarball;
+      checks.tarball = jobs.tarball;
 
       builders = {
         inherit (pkgs) stdenv fetchurl;
       };
 
+      htmlDocs = {
+        nixpkgsManual = jobs.manual;
+        nixosManual = (import ./nixos/release-small.nix {
+          nixpkgs = inputs.self;
+        }).nixos.manual.x86_64-linux;
+      };
+
       packages = {
         inherit (pkgs) hello nix fuse nlohmann_json boost firefox;
       };