refactor(docs): rename markdown packages

This makes the size report look better as the docs are grouped together.

flake-modules/docs.nix

@@ -3,14 +3,22 @@
   perSystem =
     { pkgs, ... }:
     {
-      packages = {
-        # Documentation
-        inherit (import ../docs { inherit pkgs lib; })
-          docs
-          nixos-markdown
-          nvim-markdown
-          home-markdown
-          ;
-      };
+      packages =
+        let
+          docs-pkg = import ../docs { inherit pkgs lib; };
+          inherit (docs-pkg)
+            docs
+            home-markdown
+            nixos-markdown
+            nvim-markdown
+            ;
+        in
+        {
+          # Documentation
+          inherit docs;
+          docs-home-markdown = home-markdown;
+          docs-nixos-markdown = nixos-markdown;
+          docs-nvim-markdown = nvim-markdown;
+        };
     };
 }