chore: add removeListener typings

Related: DefinitelyTyped/DefinitelyTyped#55968

index.d.ts

@@ -0,0 +1,18 @@
+interface Emitter<Event = string> {
+    on(event: Event, listener: Function): Emitter;
+    once(event: Event, listener: Function): Emitter;
+    off(event?: Event, listener?: Function): Emitter;
+    emit(event: Event, ...args: any[]): Emitter;
+    listeners(event: Event): Function[];
+    hasListeners(event: Event): boolean;
+    removeListener(event?: Event, listener?: Function): Emitter;
+    removeEventListener(event?: Event, listener?: Function): Emitter;
+    removeAllListeners(event?: Event): Emitter;
+}
+
+declare const Emitter: {
+    (obj?: object): Emitter;
+    new (obj?: object): Emitter;
+};
+
+export = Emitter;

package.json

@@ -13,6 +13,7 @@
     }
   },
   "main": "index.js",
+  "types": "index.d.ts",
   "repository": {
     "type": "git",
     "url": "https://github.com/component/emitter.git"
@@ -22,6 +23,7 @@
   },
   "files": [
     "index.js",
+    "index.d.ts",
     "LICENSE"
   ]
 }