getting started: write web app section

Closes T1193

docs/getting-started.rst

@@ -210,4 +210,33 @@ next one.
 Step 4 --- browse the archive
 -----------------------------
 
-**TO BE WRITTEN**
+You can now setup a local web app to browse what you have locally archived. The
+web app uses the configuration file ``~/.config/swh/webapp/webapp.yml``. Create
+it and fill it with something like::
+
+  storage:
+    cls: remote
+    args:
+      url: http://localhost:5002
+
+Nothing new here, the configuration just references the local storage server,
+which have been used before for repository ingestion.
+
+Before running the web app you need to compile various web assets into a
+compact webpack, like this::
+
+  cd swh-web
+  make build-webpack-dev
+
+You can now run the web app, and browse your local archive::
+
+  make run-django-webpack-devserver
+  xdg-open http://localhost:5004
+
+As an initial tour of the web app, try searching for one of the repositories
+you have ingested (e.g., entering the ``hylang`` or ``ocaml`` keywords in the
+search bar). Clicking on the repository name you will be brought back in time,
+and you will be able to browse the source code and development history you have
+archived.
+
+Enjoy!