Added docs for new notification MODULE_DOM_UPDATED (#262)

* Bump send and express (#260)

Bumps [send](https://github.com/pillarjs/send) and [express](https://github.com/expressjs/express). These dependencies needed to be updated together.

Updates `send` from 0.18.0 to 0.19.0
- [Release notes](https://github.com/pillarjs/send/releases)
- [Changelog](https://github.com/pillarjs/send/blob/master/HISTORY.md)
- [Commits](pillarjs/send@0.18.0...0.19.0)

Updates `express` from 4.20.0 to 4.21.0
- [Release notes](https://github.com/expressjs/express/releases)
- [Changelog](https://github.com/expressjs/express/blob/4.21.0/History.md)
- [Commits](expressjs/express@4.20.0...4.21.0)

---
updated-dependencies:
- dependency-name: send
  dependency-type: indirect
- dependency-name: express
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* Added docs for new notification - . Fixes #261

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

development/core-module-file.md

@@ -332,6 +332,8 @@ Whenever your module need to be updated, call the `updateDom(speed)` method. It
 requests the MagicMirror core to update its dom object. If you define the speed,
 the content update will be animated, but only if the content will really change.
 
+Note that the rendering of the updated dom on the screen will happen asynchronously. You can listen for the [`DOM_OBJECTS_UPDATED` notification](/development/notifications.html) to know when the rendering is complete and the new dom is safe to interact with. This notification only fires if the content will really change.
+
 As an example: the clock modules calls this method every second:
 
 ```javascript

development/notifications.md

@@ -22,10 +22,11 @@ The system sends three notifications when starting up:
 | `ALL_MODULES_STARTED` | _none_  | All modules are started. You can now send notifications to other modules.              |
 | `DOM_OBJECTS_CREATED` | _none_  | All dom objects are created. The system is now ready to perform visual changes.        |
 | `MODULE_DOM_CREATED`  | _none_  | This module's dom has been fully loaded. You can now access your module's dom objects. |
+| `MODULE_DOM_UPDATED`  | _none_  | This module's dom has been updated and re-rendered. You can now access your module's (updated) dom objects. This notification is sent in response to a call to [`updateDom`](https://docs.magicmirror.builders/development/core-module-file.html#module-instance-methods). |
 
 # Default module notifications
 
-These notifications are send by the default modules:
+These notifications are sent by the default modules:
 
 | Notification           | Payload                                                                                                                | Description                                                                                                                                                                                                         |
 | ---------------------- | ---------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |