Thought I'd take a moment to point out that because the Encumbrance rating on the character sheet for Roll20 is auto-calculated from weapons and equipment, and because treasure weighs 1 point of encumbrance per point of treasure, writing Treasure as an item on the equipment list, and using the number of treasure as the encumbrance value, will automatically include its weight in the companion's Encumbrance.

Furthermore, some companions have special powers that make them capable of carrying more, in that case you can write in the special ability in the equipment list as well, giving it a negative value.