chore: add explanation to user roles (#698)

Katie Horne · web-flow · commit eb542112849f · 2021-11-08T08:42:17.000-06:00
diff --git a/admin/access-control/user-roles.md b/admin/access-control/user-roles.md
@@ -39,6 +39,20 @@ There are four roles available:
     </tbody>
 </table>
 
+### Additive permissions
+
+The following tables detail what permissions Coder grants to each of the four
+roles, but a summary of the roles are:
+
+- All users are (or have the permissions of) a **member**
+- An **auditor** has the permissions of a member, plus the ability to work with
+  audit logs
+- A **site manager** has the permissions of a member or an auditor, plus
+  additional administrative rights
+- A **site admin** has the permissions of a member, auditor, and site manager,
+  as well as additional admin rights (e.g., creating site managers, access to
+  API keys)
+
 ### Site admin permissions
 
 <table>
