[IMP] tutorials: add example code for LazyComponent

js framework/Build a Dashboard/part 8 (LazyComponent)

There is no explicit instructions on how to use `LazyComponent`.

- add an example code snippet for minimal use of `LazyComponent`
- add the `.js` extension to the file you're supposed to create to make it a bit more intuitive
- fix `actions` registry name (missing an s)
- reword instructions in a more straightforward way

closes odoo/documentation#9521

Signed-off-by: Florent Dardenne (dafl) <dafl@odoo.com>

content/developer/tutorials/discover_js_framework/02_build_a_dashboard.rst

@@ -322,17 +322,31 @@ of our users. In that case, it could make sense to lazy load our dashboard, and
 related assets, so we only pay the cost of loading the code when we actually want to
 look at it.
 
-To do that, we will need to create a new bundle containing all our dashboard assets,
+One way to do this is to use `LazyComponent` (from `@web/core/assets`) as an intermediate
-then use the `LazyComponent` (located in `@web/core/assets`).
+that will load an asset bundle before displaying our component.
+
+.. example::
+
+   :file:`example_action.js`:
+
+   .. code-block:: javascript
+
+      export class ExampleComponentLoader extends Component {
+          static components = { LazyComponent };
+          static template = xml`
+              <LazyComponent bundle="'example_module.example_assets'" Component="'ExampleComponent'" />
+          `;
+      }
+
+      registry.category("actions").add("example_module.example_action", ExampleComponentLoader);
 
 #. Move all dashboard assets into a sub folder :file:`/dashboard` to make it easier to
    add to a bundle.
 #. Create a `awesome_dashboard.dashboard` assets bundle containing all content of
-   the `/dashboard` folder.
+   the :file:`/dashboard` folder.
-#. Modify :file:`dashboard.js` to register itself in the `lazy_components` registry, and not
+#. Modify :file:`dashboard.js` to register itself to the `lazy_components` registry instead of `actions`.
-   in the `action` registry.
+#. In :file:`src/dashboard_action.js`, create an intermediate component that uses `LazyComponent` and
-#. Add in :file:`src/` a file :file:`dashboard_action` that imports `LazyComponent` and registers
+   register it to the `actions` registry.
-   it to the `action` registry
 
 9. Making our dashboard generic
 ===============================