Add highlights section to changelog (#1382)

* Add highlights section

* Add missing points

* Apply suggestions from code review

Co-authored-by: Jeremy Tuloup <[email protected]>

---------

Co-authored-by: Jeremy Tuloup <[email protected]>

CHANGELOG.md

@@ -1,4 +1,55 @@
-# Changelog
+# Voila Changelog
+
+## 0.5.0 - Highlights
+
+Below are the major highlights in Voila 0.5.0
+
+### New JupyterLab-based frontend
+
+In 0.5.0, the frontend of Voila is rebuilt from scratch with JupyterLab 4.0 components. The current `requirejs` + `nbextensions` approach is replaced by a JupyterLab plugin-based application.
+This allows Voila to profit from all the upstream features and improvements.
+
+### New extension loading system.
+
+This is a direct benefit of the new frontend, now Voila will use the same prebuilt extension system as in JupyterLab.
+The extension assets are loaded from the local path instead of the CDN. This greatly improves the extension compatibility of Voila and avoid making requests to external services.
+And moreover, we can start creating extensions for Voila in the same fashion as JupyterLab extensions.
+
+### Make use of JupyterLab mimetype renderers.
+
+In 0.5.0, the logic for rendering cell outputs is switched from relying on nbconvert for handling different mimetypes to relying on JupyterLab mimetype renderers.
+This adds support for many custom JupyterLab renderers like `jupyterlab-fasta`, `vega`, `jupyterlab-geojson`...
+
+### New tree page.
+
+The default tree page of Voila is now a JupyterLab-based application using the file browser widget.
+
+The jinja-based tree page is still supported, but users need to activate it with the `--classic-tree` CLI option, the `VoilaConfiguration.classic_tree` config, or `?classic-tree=True` in the query string.
+
+JupyterLab custom themes are supported with the new tree page, for the classic tree page, only the light and dark themes are supported.
+
+### New token-based authentication system.
+
+By using `jupyter-server` 2, Voila now supports token authentication, but it is disabled by default.
+
+- To start Voila with auto-generated token:
+
+```
+voila --token notebook.ipynb
+```
+
+- To start Voila with a personalized token:
+
+```
+voila --token=my-secret-token notebook.ipynb
+```
+
+### Backwards-incompatible changes.
+
+- The new tree page no longer supports templates, users need to activate the classic tree to use existing tree templates.
+- Theme argument now is the theme name displayed in JupyterLab and not the name of the theme python package.
+- Python 3.7 is no longer supported.
+- `jupyter_client` < 7.4.4 is no longer supported.
 
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