04-functions review

[nathany]

@stellentus A review of 04-functions as exists on master right now.

I would suggest including the function signature for Println in your slides before getting into what interface{} and variardic parameters are.

public functions... technically "exported" functions

are you going to show how to use godocs for exercise 1?

[stellentus]

In an earlier slide I have a lot of links to godocs. I'll be spending time at that point looking at those docs, including some time looking at Println.

I'll update "exported functions"