Update readme with widget instructions

README.md

@@ -84,12 +84,14 @@ if you are looking for inspiration.
 
 This project uses [uv](https://github.com/astral-sh/uv) for development.
 
-Run tests with:
+### Tests
 
 ```sh
 uv run pytest
 ```
 
+### Auto-generate Schema Bindings
+
 The schema bindings (`gosling/schema/`) and docs (`doc/user_guide/API.rst`) are 
 automatically generated using the following. Please do not edit these
 files directly.
@@ -99,6 +101,20 @@ files directly.
 uv run tools/generate_schema_wrapper.py <tag_name>
 ```
 
+### Widget
+
+This repo also includes an [anywidget](https://github.com/manzt/anywidget),
+built with TypeScript using the Gosling.js library. Developing the widget
+requires [Deno](https://deno.land/). Please ensure you have it installed.
+
+To modify the widget's behavior, edit `./frontend/widget.ts` and compile with:
+
+```sh
+deno task build
+```
+
+Or use `deno task dev` to "watch" as you make changes and recompile automatically.
+
 ## Release
 
 ```bash