add description of Dashboard Manager responsibilities

adapted from https://github.com/OBOFoundry/OBOFoundry.github.io/blob/master/_data/roles.yml

fixes #2236

Author: nlharris

docs/roles/DashboardManager.md

@@ -4,4 +4,7 @@ permalink: /roles/dashboard-manager
 title: Dashboard Manager
 ---
 
-The Dashboard Manager has these basic duties:
+The [OBO Foundry dashboard](https://dashboard.obofoundry.org/) checks ontologies for adherence to OBO Foundry principles. The Dashboard Manager's jobs are:
+1. Update the dashboard once per month
+1. Fix important bugs in OBO-Dashboard if they come up (should be rare)
+1. Work with OBO Ops to find people who can update the dashboard code when new principles are added or existing ones are changed.