update contributing doc (#30)

Author: trungleduc

CONTRIBUTING.md

@@ -0,0 +1,33 @@
+## Contributing
+
+### Development install
+
+- Create a Conda environment
+
+```bash
+mamba create -n specta-dev python nodejs jupyterlab "jupyterlite-core>=0.7.0" "jupyterlite-xeus>=4.0.0"
+mamba activate specta-dev
+```
+
+- Install `specta` in editable mode
+
+```bash
+pip install -e .
+```
+
+- Build and serve the demo
+
+```bash
+npm run build:demo
+cd demo
+python -m http.server -d _output
+```
+
+- After changing the source, rebuild the app and the extension then update the demo
+
+```bash
+npm run build:all:dev
+npm run update:demo
+```
+
+Calling `update:demo` instead of `build:demo` is faster as it does not rebuild the JupyterLite instance.

pyproject.toml

@@ -67,7 +67,7 @@ build_cmd = "build:all"
 npm = ["npm"]
 
 [tool.hatch.build.hooks.jupyter-builder.editable-build-kwargs]
-build_cmd = "install:extension"
+build_cmd = "build:all:dev"
 npm = ["npm"]
 source_dir = "src"
 build_dir = "specta/labextension"