Issue Summary

The option to add overrides is available for users when they navigate to the team, then attempt to update the schedule from there: 

However, if they attempt to do this via the "On-call schedules" menu, the option is missing (and there is no guidance that they should go to the team to do this). 

Steps to Reproduce

1. Go to a JSM Operations instance 
2. Click on "Operations" > "On-call schedules" from the left 
3. Notice there is no option to override the schedule 
4. Go to Operations in a team, and notice there is an option to add override 

Expected Results

If the "on-call schedules" is a read-only mode, please add a moniker to state this, and direct users to go into the team to add their override. Otherwise, please add the "add override" option on this screen as well for consistency and ease of use.

Actual Results

No override button in the "on-call schedules" screen. 

Workaround

Go into the team and add override to schedule from there.