Add instructions to generate the documentation locally (#77)

* Add instructions to generate the documentation locally

* Add instructions about PR rendered doc

README.md

@@ -24,3 +24,37 @@ better a [Pull Request (PR)](https://github.com/jean-zay-users/jean-zay-doc/comp
 
 We use gitter for chat, don't hesitate to get involved
 [there](https://gitter.im/jean-zay-users/jean-zay-doc) and ask questions!
+
+# See the generated doc in a PR
+
+You can see the generated doc in a PR at the bottom of the PR page. This allows
+you to double-check that the rendered HTML looks the way you intended.
+
+It will look like the screenshot below. To view the generated doc you can click
+on the "Details" link:
+![](https://user-images.githubusercontent.com/1680079/146903507-d56addb6-c038-4d01-a151-933a8f261af2.png)
+
+You can also generate the doc locally, see [this](#generating-the-doc-locally)
+for instructions.
+
+# Generating the doc locally
+
+The documentation is using [mkdocs](https://www.mkdocs.org/) with a few
+plugins. To install them:
+```
+pip install -e requirements.txt
+```
+
+To run `mkdocs` in development mode:
+```
+mkdocs serve
+```
+
+This launches a local server so that you can view the generated docs in your
+browser. One very convenient feature to work on the doc is that the rendered
+HTML is updated automatically when you change a `.md` file, so you can quickly
+see the impact of your changes. The URL of the local server will be shown in
+the output of the `mkdocs serve` command, for example:
+```
+INFO     -  [15:07:11] Serving on http://127.0.0.1:8000/
+```

requirements.txt

@@ -0,0 +1,3 @@
+mkdocs
+mkdocs-material
+mkdocs-macros-plugin