docs: add local development instructions

README.md

@@ -1,6 +1,8 @@
 # rgbds-live
 
-A live Gameboy programming environment in the browser,allowing for realtime assembly programming for the gameboy. Powered by webassembly builds of RGBDS and the Binjgb emulator.
+A live Gameboy programming environment in the browser, allowing for realtime assembly programming for the gameboy. Powered by webassembly builds of [RGBDS](https://rgbds.gbdev.io/) and the [Binjgb](https://github.com/binji/binjgb) emulator.
+
+Try online at [gbdev.io/rgbds-live](https://gbdev.io/rgbds-live/).
 
 ## Build
 
@@ -9,3 +11,13 @@ System requirements:
 - bison, cmake
 - [emscripten](https://emscripten.org/docs/getting_started/downloads.html)
 
+To build RGBDS live and run it locally:
+
+```bash
+# Pull RGBDS-live, rgbds and binjgb sources
+https://github.com/gbdev/rgbds-live
+# Generate WASM builds and put them in the main source folder
+./build.sh
+```
+
+Final build will be in `www/`. You can run the provided `serve-site.sh` to serve that folder locally over port 8080.