Documentation of variable use

[rjspotter]

The README claims that to see a full-blown example of variable change triggering re-execution of the query one should look at the third example. The third example is no different from the second example and does not use bound variables in it's query.

[paales]

It seems i've never finished the documentation. Planning on doing some work soon to also include the latest Apollo client 2.0. Will update that example as well.