A covenant is a solemn agreement. Teaching others about the Good News and living the Christian life is about the most solemn thing I can imagine. In the church we deal with the eternal. Can you name something more solemn than the eternal.
Attached is a sample pdf copy of a covenant for Bible study Leaders. It can be used as an example to write a covenant for any leadership groups of your organization.
More important than specific wording in a covenant is the fact that the leaders understand the importance of commitment to growing others in their spiritual walk.