Coding Session: Sign up UI updates

I updated the sign up TextFields to remove the unnecessary labels because it will create a conflict between the two when the user taps on it. Also, implemented the return key type for each TextFields, for those who are not familiar these are the small buttons on the lower right most in iPhone's keyboard with the "return" button.

Loom: https://www.loom.com/share/6cffcf5afcf74c0aa197659ea0239cf1