Splitting the code examples into modules

[alexmozaidze]

I am trying to reason about slash commands and how to handle them with this library, but it was quite difficult to do because of how slash_commands/main.go was stuffed up by the irrelevant for me things. I understand that it attempts to show all the capabilities of the library, but I need a small portion of its functionality. Could you, perhaps, split this example into sub-examples?

I very much like the library, keep up the good work!

[JadeMin]

+1 i really want this.