Clarify that <script type=webbundle> doesn't fire a load nor an error…

… event (WICG#696)

* Clarify that <script type=webbundle> doesn't fire a load event

issue WICG#670.

* Mention an error event and issue WICG#697

explainers/subresource-loading.md

@@ -172,6 +172,14 @@ using document's [base URL](https://html.spec.whatwg.org/#document-base-url).
 
 `<script type="webbundle">` doesn't support `src=` attribute. The rule must be inline.
 
+`<script type="webbundle">` doesn't fire a `load` event nor an `event` event.
+
+Note: We could fire `load` and `error` events if we wanted to. See [issue
+#697](https://github.com/WICG/webpackage/issues/697)
+
+Note that neither `<script type=importmaps>` nor `<script type=speculationrules>`
+fires a `load` event for an inline rule.
+
 ## Request's mode and credentials mode
 
 A [request](https://fetch.spec.whatwg.org/#concept-request) for a bundle