Add @Event documentation to all LanguageConfigOverrideEvents

This issue is for adding the @Event tag and appropriate documentation to the following list of events.

$this->eventDispatcher->dispatch(LanguageConfigOverrideEvents::DELETE_OVERRIDE, new LanguageConfigOverrideCrudEvent($this));
$this->eventDispatcher->dispatch(LanguageConfigOverrideEvents::SAVE_OVERRIDE, new LanguageConfigOverrideCrudEvent($this));

This documentation should include the following information:

- What the event is
- What it is used for
- What kind of $event object is passed along.
- @see links to related classes (event class, representative class where event is dispatched, representative class where event is subscribed to).

Beta eval: This is API documentation, so unfrozen. Also very low disruption possibility.

See the parent issue for a documentation template, and more information: #2382169: [meta] Add @Event to all events defined by drupal core