Many statblocks in `monsters.json` are missing the modifier for their `hit_dice` field

[cynicaloptimist]

https://github.com/eepMoody/open5e-api/blob/master/data/WOTC_5e_SRD_v5.1/monsters.json A few examples include the Bandit and Knight statblocks, but any instance of the hit_dice field where there is no modifier is probably affected by this.

Improved Initiative uses the hit_dice field when rolling random monster HP so the modifier is important. https://github.com/cynicaloptimist/improved-initiative/issues/580

Thanks!