docs(overlays): clarify how to remove an overlay (#28989)

In https://github.com/ionic-team/ionic-framework/issues/28981 there was
some confusion surrounding how to remove an overlay from the DOM if it
was never presented. The `dismiss` method will remove the overlay from
the DOM, but only if the overlay is visible. Otherwise, it's a no-op.

This PR updates the `dismiss` method docs for each overlay component to
note that developers can use the browser's remove method to remove the
element from the DOM.

core/src/components/popover/popover.tsx

@@ -525,6 +525,10 @@ export class Popover implements ComponentInterface, PopoverInterface {
    * @param role The role of the element that is dismissing the popover. For example, 'cancel' or 'backdrop'.
    * @param dismissParentPopover If `true`, dismissing this popover will also dismiss
    * a parent popover if this popover is nested. Defaults to `true`.
+   *
+   * This is a no-op if the overlay has not been presented yet. If you want
+   * to remove an overlay from the DOM that was never presented, use the
+   * [remove](https://developer.mozilla.org/en-US/docs/Web/API/Element/remove) method.
    */
   @Method()
   async dismiss(data?: any, role?: string, dismissParentPopover = true): Promise<boolean> {