Fix typos in ShallowWrapper/forEach docs example
Fix typos in ShallowWrapper/forEach docs example

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

toddw/enzyme,hartzis/enzyme,dustinsanders/enzyme,airbnb/enzyme,airbnb/enzyme,CurtisHumphrey/enzyme,seejee/enzyme,seejee/enzyme,CurtisHumphrey/enzyme,hartzis/enzyme,dustinsanders/enzyme,toddw/enzyme