typings(WebhookClient): client is not a Client (#3829)

* typings(WebhookClient): client is not a Client

* style: use tabs

Author: NotSugden

typings/index.d.ts

@@ -303,13 +303,6 @@ declare module 'discord.js' {
 		public toString(): string;
 	}
 
-	export interface ActivityOptions {
-		name?: string;
-		url?: string;
-		type?: ActivityType | number;
-		shardID?: number | number[];
-	}
-
 	export class ClientUser extends User {
 		public mfaEnabled: boolean;
 		public verified: boolean;
@@ -1630,6 +1623,7 @@ declare module 'discord.js' {
 	export class WebhookClient extends WebhookMixin(BaseClient) {
 		constructor(id: string, token: string, options?: ClientOptions);
 		public token: string;
+		public readonly client: this;
 	}
 
 	export class WebSocketManager extends EventEmitter {
@@ -1923,6 +1917,13 @@ declare module 'discord.js' {
 		| 'SYNC'
 		| 'PLAY';
 
+	interface ActivityOptions {
+		name?: string;
+		url?: string;
+		type?: ActivityType | number;
+		shardID?: number | number[];
+	}
+
 	type ActivityType = 'PLAYING'
 		| 'STREAMING'
 		| 'LISTENING'