Document the command to launch JupyterLab and watch for changes to the backend code for server extensions (#274)

* Document the command to launch JupyterLab and watch for changes to the backend code for server extensions

* Add missing ToC entry

Author: joaopalmeiro

server-extension/README.md

@@ -14,6 +14,7 @@ example before diving into this one.
   - [Packaging the Extension](#packaging-the-extension)
     - [Python Package Manager](#python-package-manager)
     - [JupyterLab Extension Manager](#jupyterlab-extension-manager)
+  - [Development](#development)
   - [Installing the Package](#installing-the-package)
 
 ## The template folder structure
@@ -565,7 +566,7 @@ done using [hatch](https://hatch.pypa.io/) builder with some additional plugins:
 - [hatch-jupyter-builder](https://github.com/jupyterlab/hatch-jupyter-builder/): Builder plugin to build Jupyter JavaScript assets as part of the Python package.
   Its configuration is done in `pyproject.toml`:
 
-```
+```toml
 # pyproject.toml
 
 [build-system]
@@ -758,6 +759,18 @@ And that server extension is available through `pip`:
 
 For more information on the `discovery` metadata, please refer to the [documentation](https://jupyterlab.readthedocs.io/en/stable/extension/extension_dev.html#ext-author-companion-packages).
 
+## Development
+
+While developing your server extension, you can run JupyterLab and enable server reloading using the following command:
+
+```bash
+jupyter lab --autoreload --no-browser
+```
+
+This way, every time there is a change to the backend (server) code, JupyterLab is automatically relaunched, picking up the most recent changes.
+
+The `--no-browser` flag is optional, but it helps prevent a new browser tab from opening each time JupyterLab is launched.
+
 ## Installing the Package
 
 With the packaging described above, installing the extension is done in one command once the package is published on pypi.org: