Fix scroll to symbol's documentation

doc/classes/RichTextLabel.xml

@@ -712,6 +712,7 @@
 		<signal name="finished">
 			<description>
 				Triggered when the document is fully loaded.
+				[b]Note:[/b] This can happen before the text is processed for drawing. Scrolling values may not be valid until the document is drawn for the first time after this signal.
 			</description>
 		</signal>
 		<signal name="meta_clicked">

editor/editor_help.cpp

@@ -270,7 +270,7 @@ void EditorHelp::_search(bool p_search_previous) {
 
 void EditorHelp::_class_desc_finished() {
 	if (scroll_to >= 0) {
-		class_desc->scroll_to_paragraph(scroll_to);
+		class_desc->connect(SceneStringName(draw), callable_mp(class_desc, &RichTextLabel::scroll_to_paragraph).bind(scroll_to), CONNECT_ONE_SHOT | CONNECT_DEFERRED);
 	}
 	scroll_to = -1;
 }