Clarifying instructions for Travis to automatically publish the documentation online

[richardreeve]

As a follow-up to #237, here is some additional documentation along with REPL output explaining how to get Travis to talk to github. It also deletes the docs on using github security tokens.

[MichaelHatherly]

Excellent, thanks!

Feel free to ignore it if it's not what you're looking for.

No, this is pretty much what I had in mind 👍. Only bit that could probably be clarified is the [...] that is being used to represent the ssh keys. Can you add a note after its first appearance just to explain that it isn't the actual output users should expect.

[richardreeve]

Okay, I've removed one of the [...] sections and explained the second.

[MichaelHatherly]

Thanks, LGTM.