fix: add role fallback value for legend (#702)

Co-authored-by: Fei <[email protected]>

Author: Fei Z

Diff for: packages/core/src/components/essentials/legend.ts

@@ -20,7 +20,7 @@ export class Legend extends Component {
 	render() {
 		const svg = this.getContainerSVG().attr(
 			"role",
-			Roles.GRAPHICS_DOCUMENT
+			`${Roles.GRAPHICS_DOCUMENT} ${Roles.DOCUMENT}`,
 		);
 		const options = this.model.getOptions();
 		const legendOptions = Tools.getProperty(options, "legend");

Diff for: packages/core/src/interfaces/a11y.ts

@@ -2,5 +2,6 @@ export enum Roles {
 	GRAPHICS_DOCUMENT = "graphics-document",
 	GRAPHICS_OBJECT = "graphics-object",
 	GRAPHICS_SYMBOL = "graphics-symbol",
-	GROUP = "group"
+	GROUP = "group",
+	DOCUMENT = "document"
 }