Paladin: Clarify when to use retribution CDs while GoAK is active.

We wait for Ancient Power to stack up to max to gain the full benefit of
Guardian of Ancient Kings, or otherwise use the CD so that it doesn't run
out before GoAK expires.
Rogue: Fix Envenom usage at execute range.

When the target was below 35% health, the script was incorrectly
suggesting Envenon all of the time instead of waiting for 5 CPs.