Move the xkcd credit to a footnote

[djmitche]

Since this is a joke, delivery is important, and putting the credit in the middle of the joke kind of ruins that delivery. Hopefully this duly credits Munroe while still preserving the humor!

/cc @TPReal who suggested the credit initially in #748.

[TPReal]

My first thought to the suggestion of putting the reference "on the line before the 4" was that it would kind of ruin the joke. But then I phrased it as "Implementation based on ..." and for me that is one-and-a-half jokes at the cost of one, and I liked it. But I'm fine with the change if you really think it's better this way.

[mgeisler]

But then I phrased it as "Implementation based on ..." and for me that is one-and-a-half jokes at the cost of one, and I liked it.

I actually read it the same way: the comment is extra funny now because it pretends to be a "serious" comment :smile: Similar to when an academic paper for some RNG or crypto implementation.

At first I felt that having a comment would take away from the joke, but this comment is actually nice.

[djmitche]

ah, ok, let's leave it then!