Backport: Guild#createChannel (#2145)

* Backport: Guild#createChannel

* this should not return a buffer

src/structures/Guild.js

@@ -873,11 +873,19 @@ class Guild {
     if (!this.client.user.bot) this.client.syncGuilds([this]);
   }
 
+  /**
+   * Can be used to overwrite permissions when creating a channel.
+   * @typedef {Object} ChannelCreationOverwrites
+   * @property {PermissionResolvable[]|number} [allow] The permissions to allow
+   * @property {PermissionResolvable[]|number} [deny] The permissions to deny
+   * @property {RoleResolvable|UserResolvable} id ID of the role or member this overwrite is for
+   */
+
   /**
    * Creates a new channel in the guild.
    * @param {string} name The name of the new channel
    * @param {string} type The type of the new channel, either `text` or `voice` or `category`
-   * @param {Array<PermissionOverwrites|Object>} [overwrites] Permission overwrites to apply to the new channel
+   * @param {Array<PermissionOverwrites|ChannelCreationOverwrites>} [overwrites] Permission overwrites
    * @param {string} [reason] Reason for creating this channel
    * @returns {Promise<TextChannel|VoiceChannel>}
    * @example

src/structures/GuildChannel.js

@@ -155,7 +155,7 @@ class GuildChannel extends Channel {
    * @param {Role|Snowflake|UserResolvable} userOrRole The user or role to update
    * @param {PermissionOverwriteOptions} options The configuration for the update
    * @param {string} [reason] Reason for creating/editing this overwrite
-   * @returns {Promise}
+   * @returns {Promise<GuildChannel>}
    * @example
    * // Overwrite permissions for a message author
    * message.channel.overwritePermissions(message.author, {
@@ -203,7 +203,7 @@ class GuildChannel extends Channel {
       }
     }
 
-    return this.client.rest.methods.setChannelOverwrite(this, payload, reason);
+    return this.client.rest.methods.setChannelOverwrite(this, payload, reason).then(() => this);
   }
 
   /**