build(docs): use mkdocs from nixpkgs instead of docker

Makefile

@@ -53,13 +53,7 @@ dev:
 	make -C bootstrap
 
 docs:
-	docker run \
-		--rm \
-		--interactive \
-		--tty \
-		--publish 8000:8000 \
-		--volume $(shell pwd):/docs \
-		squidfunk/mkdocs-material
+	mkdocs serve
 
 git-hooks:
 	pre-commit install

shell.nix

@@ -5,6 +5,7 @@ let
   python-packages = pkgs.python3.withPackages (p: with p; [
     jinja2
     kubernetes
+    mkdocs-material
     netaddr
     rich
   ]);