Updated readme example's async example to use IIFE

[mattwelke]

I notice the first example uses a series of statements (which would perform the action), but the second example, showcasing async/await syntax, uses a function definition instead. If someone ran the code examples, they would not do the same thing, especially if one extended the example with statements inside the if bodies.

I changed the second example to align with the first. Same style (semicolons, function instead of arrow function, etc), but the second example now also shows code that "does stuff".

[coveralls]

Coverage remained the same at 92.308% when pulling 1f72eb1 on welkie:master into f3d4c79 on normalize:master.