Add default.nix and udpate README

README.md

@@ -14,6 +14,14 @@ To generate HTML version:
     # open _build/index.html in your browser
     ```
 
+If you use [nix](https://nixos.org/nix/), you can just run:
+
+```
+  nix-shell
+```
+
+This will build the docs and start a livereload server on `http://localhost:5500`.
+
 ---
 
 **Sphinx Installation Notes:**

default.nix

@@ -0,0 +1,14 @@
+with import <nixpkgs> {};
+
+stdenv.mkDerivation {
+  name = "postgrest-docs";
+  buildInputs = [
+    python36Full
+    python36Packages.sphinx
+    python36Packages.sphinx_rtd_theme
+    python36Packages.livereload ];
+  shellHook = ''
+    sphinx-build -b html -a -n . _build
+    python reload_docs.py && exit
+  '';
+}