Added ability to specify position when creating a channel

src/Discord.Net.Rest/API/Rest/CreateGuildChannelParams.cs

@@ -12,6 +12,8 @@ namespace Discord.API.Rest
         public ChannelType Type { get; }
         [JsonProperty("parent_id")]
         public Optional<ulong?> CategoryId { get; set; }
+        [JsonProperty("position")]
+        public Optional<int> Position { get; set; }
 
         //Text channels
         [JsonProperty("topic")]

src/Discord.Net.Rest/Entities/Guilds/GuildHelper.cs

@@ -163,6 +163,7 @@ namespace Discord.Rest
                 CategoryId = props.CategoryId,
                 Topic = props.Topic,
                 IsNsfw = props.IsNsfw,
+                Position = props.Position
             };
             var model = await client.ApiClient.CreateGuildChannelAsync(guild.Id, args, options).ConfigureAwait(false);
             return RestTextChannel.Create(client, guild, model);
@@ -180,7 +181,8 @@ namespace Discord.Rest
             {
                 CategoryId = props.CategoryId,
                 Bitrate = props.Bitrate,
-                UserLimit = props.UserLimit
+                UserLimit = props.UserLimit,
+                Position = props.Position
             };
             var model = await client.ApiClient.CreateGuildChannelAsync(guild.Id, args, options).ConfigureAwait(false);
             return RestVoiceChannel.Create(client, guild, model);