Muchas gracias! I've been looking for something like that. Another interesting bit I learned from the link:
> While orbits about the L2 point are inherently unstable, the orbit size is large and the orbital velocity is low (~1 km/s), so the orbit "decays" slowly. However, JWST's large sun shield, roughly the size of a tennis court, is subject to significant solar radiation pressure which results in both a force and a torque. The direction of solar force varies as the observatory's attitude changes from observation to observation. The solar torque is balanced by reaction wheels, but periodically, the accumulated momentum is dumped by firing thrusters.
If I understand correctly: JWST needs thrusters not to counteract a decaying orbit (too little energy), but to counteract accumulated momentum from solar radition (too much energy).