Storybook: Add stories for URLInputButton component

packages/block-editor/src/components/url-input/stories/button.story.js

@@ -0,0 +1,44 @@
+/**
+ * Internal dependencies
+ */
+import URLInputButton from '../button';
+
+const meta = {
+	title: 'BlockEditor/URLInputButton',
+	component: URLInputButton,
+	parameters: {
+		docs: {
+			canvas: { sourceState: 'shown' },
+			description: {
+				component:
+					'Render a URL input button that pops up an input to search for and select a post or enter any arbitrary URL.',
+			},
+		},
+	},
+	argTypes: {
+		url: {
+			control: 'text',
+			description:
+				'This should be set to the attribute (or component state) property used to store the URL.',
+			type: {
+				required: true,
+				name: 'string',
+			},
+		},
+		onChange: {
+			control: {
+				type: null,
+			},
+			description: `Called when the value changes. The second parameter is null unless the user selects a post from the suggestions dropdown.`,
+			type: {
+				required: true,
+				name: 'function',
+			},
+			action: 'onChange',
+		},
+	},
+};
+
+export default meta;
+
+export const Default = {};