kill-ring-max is a thing

So I recently discovered the variable `kill-ring-max', that dictates the size of the kill-ring, meaning when items on the kill-ring will be discarded.  Its original value is 60, and for some reason I still had it set to the default.

It's strange that I hadn't seen it mentioned before (at least, enough times to pay attention to it,) so let's try to increase the awareness of this very useful variable.

If you use helm-show-kill-ring, or something that allows you to search through kill-ring, having a bigger kill-ring might allow you to recover s"lost" work.