Add XML docs to small session model types and remove CS1591 suppressions

MediaBrowser.Model/Session/RepeatMode.cs

@@ -1,11 +1,23 @@
-#pragma warning disable CS1591
-
 namespace MediaBrowser.Model.Session
 {
+    /// <summary>
+    /// The repeat mode of a play queue.
+    /// </summary>
     public enum RepeatMode
     {
+        /// <summary>
+        /// Nothing is repeated.
+        /// </summary>
         RepeatNone = 0,
+
+        /// <summary>
+        /// The whole queue is repeated.
+        /// </summary>
         RepeatAll = 1,
+
+        /// <summary>
+        /// The current item is repeated.
+        /// </summary>
         RepeatOne = 2
     }
 }