docs(prefer-expect-resolves): adjust incorrect example snippet (#1253)

Author: G-Rath

docs/rules/prefer-expect-resolves.md

@@ -58,6 +58,8 @@ it('is true', async () => {
 });
 
 it('errors', async () => {
-  await expect(Promise.rejects('oh noes!')).rejects.toThrow('oh noes!');
+  await expect(Promise.reject(new Error('oh noes!'))).rejects.toThrowError(
+    'oh noes!',
+  );
 });
 ```

src/rules/__tests__/prefer-expect-resolves.test.ts

@@ -27,7 +27,9 @@ ruleTester.run('prefer-expect-resolves', rule, {
     `,
     dedent`
       it('errors', async () => {
-        await expect(Promise.rejects('oh noes!')).rejects.toThrow('oh noes!');
+        await expect(Promise.reject(new Error('oh noes!'))).rejects.toThrowError(
+          'oh noes!',
+        );
       });
     `,
   ],