Update IGuildScheduledEvent.cs

src/Discord.Net.Core/Entities/Guilds/IGuildScheduledEvent.cs

@@ -86,11 +86,11 @@ namespace Discord
         int? UserCount { get; }
 
         /// <summary>
-        ///     Gets this events banner image url
+        ///     Gets this events banner image url.
         /// </summary>
         /// <param name="format">The format to return.</param>
         /// <param name="size">The size of the image to return in. This can be any power of two between 16 and 2048.
-        /// <returns></returns>
+        /// <returns>The cover images url.</returns>
         string GetCoverImageUrl(ImageFormat format = ImageFormat.Auto, ushort size = 1024);
 
         /// <summary>