add story for onScrollToBottom scenario

Author: iAmNathanJ

polaris-react/src/components/Scrollable/Scrollable.stories.tsx

@@ -154,7 +154,7 @@ export function WithHorizonalScrollPrevention() {
   );
 }
 
-export function ToChildComponent() {
+export function ScrollToChildComponent() {
   return (
     <Card title="Terms of service" sectioned>
       <Scrollable shadow style={{height: '200px'}}>
@@ -500,3 +500,30 @@ export function WithScrollHint() {
     </Card>
   );
 }
+
+export function OnScrolledToBottom() {
+  return (
+    <Card title="Terms of service" sectioned>
+      <Scrollable
+        style={{height: '200px'}}
+        onScrolledToBottom={() => console.log('scrolled to bottom')}
+      >
+        <p>
+          By signing up for the Shopify service (“Service”) or any of the
+          services of Shopify Inc. (“Shopify”) you are agreeing to be bound by
+          the following terms and conditions (“Terms of Service”). The Services
+          offered by Shopify under the Terms of Service include various products
+          and services to help you create and manage a retail store, whether an
+          online store (“Online Services”), a physical retail store (“POS
+          Services”), or both. Any new features or tools which are added to the
+          current Service shall be also subject to the Terms of Service. You can
+          review the current version of the Terms of Service at any time at
+          https://www.shopify.com/legal/terms. Shopify reserves the right to
+          update and change the Terms of Service by posting updates and changes
+          to the Shopify website. You are advised to check the Terms of Service
+          from time to time for any updates or changes that may impact you.
+        </p>
+      </Scrollable>
+    </Card>
+  );
+}