Clarifying xml doc on ScheduleStatus (#797)

Author: mathewc

src/WebJobs.Extensions/Extensions/Timers/Scheduling/ScheduleStatus.cs

@@ -6,7 +6,8 @@
 namespace Microsoft.Azure.WebJobs.Extensions.Timers
 {
     /// <summary>
-    /// Represents a timer schedule status.
+    /// Represents a timer schedule status. The scheduler uses this information to calculate
+    /// function invocation times.
     /// </summary>
     public class ScheduleStatus
     {
@@ -18,6 +19,11 @@ public class ScheduleStatus
         /// <summary>
         /// Gets or sets the expected next schedule occurrence.
         /// </summary>
+        /// <remarks>
+        /// When a function is invoked by the scheduler, the value of this property
+        /// will effectively be the current time. To determine the next schedule occurrence
+        /// from the current invocation, <see cref="TimerInfo.Schedule"/> can be used.
+        /// </remarks>
         public DateTime Next { get; set; }
 
         /// <summary>