Update Competency Objective documentation

CompetencyObjective and StudentCompetencyObjective have conflicting documentation, particularly around Learning Objectives.

• CompetencyObjective is defined as, "This entity holds additional competencies for student achievement that are not associated with specific learning objectives (e.g., paying attention in class)."
• StudentCompetencyObjective is defined as, "This entity represents the competency assessed or evaluated for the student against a specific learning objective."
• StudentCompetencyObjective.CompetencyLevel is defined as, "The CompetencyLevel assessed for the student for the referenced LearningObjective."

Assuming the CompetencyObjective definition to be correct, the StudentCompetencyObjective, and CompetencyLevel definitions should be updated to match.