Fix GetCategoryAsync docs

src/Discord.Net.Core/Entities/Channels/INestedChannel.cs

@@ -20,9 +20,9 @@ namespace Discord
         /// </summary>
         /// <param name="mode">The <see cref="CacheMode"/> that determines whether the object should be fetched from cache.</param>
         /// <param name="options">The options to be used when sending the request.</param>
-        /// <remarks>
+        /// <returns>
         ///     A category channel representing the parent of this channel; <c>null</c> if none is set.
-        /// </remarks>
+        /// </returns>
         Task<ICategoryChannel> GetCategoryAsync(CacheMode mode = CacheMode.AllowDownload, RequestOptions options = null);
     }
 }