Added and fixed a bunch of docs stuff (#1767)

- Fixed a common copy paste fail `the the <thing>` in various places
- Apparently I can't type Resolvable correctly,
Fixed that wherever applicable
- Documented GroupDMChannel#nicks so that it will be displayed on the docs
- GroupDMChannel#icon is nullable
- Removed empty InviteOptions typdef, as its properties are now documented in GuildChannel#createInvite
- MessageMentions#channels is no longer nullable
- RoleData#permissions takes a PermissionResolvable or an array of them
- Webhook#avatar is nullable
- Added HTTPOptions typedef and added it to ClientOptions typedef
- ClientUserChannelOverride#muted is for a channel and not a guild directly

src/structures/GuildChannel.js

@@ -274,15 +274,9 @@ class GuildChannel extends Channel {
     return this.edit({ topic }, reason);
   }
 
-  /**
-   * Options given when creating a guild channel invite.
-   * @typedef {Object} InviteOptions
-
-   */
-
   /**
    * Create an invite to this guild channel.
-   * @param {InviteOptions} [options={}] Options for the invite
+   * @param {Object} [options={}] Options for the invite
    * @param {boolean} [options.temporary=false] Whether members that joined via the invite should be automatically
    * kicked after 24 hours if they have not yet received a role
    * @param {number} [options.maxAge=86400] How long the invite should last (in seconds, 0 for forever)