add create and update methods

Octokit/Models/Request/UpdateTeam.cs

@@ -0,0 +1,20 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Globalization;
+
+namespace Octokit
+{
+    public class UpdateTeam
+    {
+        /// <summary>
+        /// team name
+        /// </summary>
+        public string Name { get; set; }
+
+        /// <summary>
+        /// permission for this team
+        /// </summary>
+        public Permission Permission { get; set; }
+    }
+}