Draft NOTES for 1.13.0

@mglukhovsky can you please review?

@danielmewes @Tryneus @mlucy @danielmewes @neumino @srh Please also take a look to make sure I haven't mis-characterized some of your fixes.
In Ruby you can write `r.changes(r.table('test'))` as well as `r.table('test').changes()` (in general, the Ruby driver doesn't force you to use infix method chaining).