Fixing RequirementSection/Concentration relationship
Fixing RequirementSection/Concentration relationship

Concentrations `embeds_many :requirement_sections`. So conversely, RequirementSections should be `embedded_in :concentration`

This came about here: https://github.com/biola/buweb-content-models/commit/5ddc1a2815254a04fc061feb2b19dca9ef1b5b56#diff-0db945fd16111bc4fcaebf0bec031295
biola/buweb-content-models