Document how to build/test/run docs w/Makefile

- Also update `poetry.lock` to new lock-file format for poetry
- Update poetry/mkdocs dependencies
- Update nixpkgs flake input and make `flake.nix` smaller =)

Author: x10an14-nav

Makefile

@@ -1,10 +1,12 @@
-.PHONY: all install local
-SHELL := bash
+.PHONY: build check serve install-mkdocs
 
-all: install local
-
-install:
+install-mkdocs:
 	poetry install
 
-local:
-	poetry run mkdocs serve --dev-addr localhost:8001
+build:
+	poetry run mkdocs build --strict
+
+chect: build
+
+serve:
+	poetry run mkdocs serve --clean --strict --watch docs/

flake.lock

@@ -1,37 +1,27 @@
 {
   description = "dev env for handbook";
 
-  # Flake inputs
-  inputs = {
-    nixpkgs.url = "github:NixOS/nixpkgs"; # also valid: "nixpkgs"
-  };
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs";
+  inputs.flake-utils.url = "github:numtide/flake-utils";
 
-  # Flake outputs
-  outputs = { self, nixpkgs }:
-    let
+  outputs =
+    inputs:
+    inputs.flake-utils.lib.eachSystem
       # Systems supported
-      allSystems = [
-        "x86_64-linux" # 64-bit Intel/AMD Linux
-        "aarch64-linux" # 64-bit ARM Linux
-        "x86_64-darwin" # 64-bit Intel macOS
-        "aarch64-darwin" # 64-bit ARM macOS
-      ];
-
-      # Helper to provide system-specific attributes
-      forAllSystems = f: nixpkgs.lib.genAttrs allSystems (system: f {
-        pkgs = import nixpkgs { inherit system; };
-      });
-    in
-    {
-      # Development environment output
-      devShells = forAllSystems ({ pkgs }: {
-        default =
-          pkgs.mkShell {
+      [ "x86_64-linux" "x86_64-darwin" "aarch64-linux" "aarch64-darwin" ]
+      (
+        system:
+        let
+          pkgs = import inputs.nixpkgs { localSystem = { inherit system; }; };
+        in
+        {
+          devShells.default = pkgs.mkShell {
             packages = with pkgs; [
+              # Development environment output
               python311
               poetry
             ];
           };
-      });
-    };
+        }
+      );
 }