feat: (src/5e-SRD-Monsters.json): added modifiers to hit dice (#500)

* Added modifiers to hit dice per SRD

* fix(5e-SRD-Monsters.json):Added modifiers to hit dice per SRD

* fix(src/5e-SRD-Monsters.json): Added hit_roll_dice attribute which includes modifier for CON

* fix(src/5e-SRD-Monsters.json): Added hit_points_roll  attribute which includes modifier for CON

* fix(src/5e-SRD-Monsters.json): Added hit_points_roll  attribute which includes modifier for CON-- formatted JSON file

* Replaced erroneous unicode characters with the characters as they appear in main branch version of the monsters source json

Author: Stuart-Yee