Fix typos in ShallowWrapper/forEach docs example

- Replace `s` with `node` within iteration
- Adds missing `.` within `expect(/**/).to.be.true`

docs/api/ShallowWrapper/forEach.md

@@ -30,7 +30,7 @@ const wrapper = shallow(
 );
 
 wrapper.find('.foo').forEach(function (node) {
-  expect(s.hasClass('foo')).to.be true;
+  expect(node.hasClass('foo')).to.be.true;
 });
 ```