Fix README example

Author: MatheusRich

README.md

@@ -50,11 +50,11 @@ class User
   attributes :name, :age, email: 'guest@user.com'
 end
 
-User.new(name: 'Matz', age: 22)
+user = User.new(name: 'Matz', age: 22)
 # => #<User:0x000055bac152f130 @name="Matz", @age=22, @email="guest@user.com">
 
 # EzAttributes will add getters for all fields too.
-User.name
+user.name
 # => "Matz"
 ```