Add streaming analytics doc page

This will probably become a blogpost (though not until the work is actually in to the various `*toolz` projects.)

@eigenhombre The join PR benefited significantly from your comments.  Your perspective would be appreciated here.
This sounds awkward to me.  Is example singular or plural?  Also, I think you meant to use comprise, not compose.  To illustrate: the parts compose the whole, but the whole comprises the parts.