[Service Bus] Retry Options Docs (Azure#21653)

The focus of these changes is to document the default value used for each
property of the `ServiceBusRetryOptions`.

Author: jsquire

sdk/servicebus/Azure.Messaging.ServiceBus/src/Primitives/ServiceBusRetryOptions.cs

@@ -36,6 +36,9 @@ public class ServiceBusRetryOptions
         ///   to have failed.
         /// </summary>
         ///
+        ///
+        /// <value>The default retry limit is 3.</value>
+        ///
         public int MaxRetries
         {
             get => _maxRetries;
@@ -52,6 +55,9 @@ public int MaxRetries
         ///   on which to base calculations for a backoff-based approach.
         /// </summary>
         ///
+        ///
+        /// <value>The default delay is 0.8 seconds.</value>
+        ///
         public TimeSpan Delay
         {
             get => _delay;
@@ -67,6 +73,9 @@ public TimeSpan Delay
         ///   The maximum permissible delay between retry attempts.
         /// </summary>
         ///
+        ///
+        /// <value>The default maximum delay is 60 seconds.</value>
+        ///
         public TimeSpan MaxDelay
         {
             get => _maxDelay;
@@ -83,6 +92,9 @@ public TimeSpan MaxDelay
         ///   attempt or a retry.
         /// </summary>
         ///
+        ///
+        /// <value>The default timeout is 60 seconds.</value>
+        ///
         public TimeSpan TryTimeout
         {
             get => _tryTimeout;