added missing collection endpoints

src/endpoints/collections.ts

@@ -1,4 +1,4 @@
-import { DetailedCollection, LanguageOption, PageOption } from '../types';
+import { DetailedCollection, ImageCollection, LanguageOption, PageOption, Translations } from '../types';
 import {  BaseEndpoint } from './base';
 import querystring from 'querystring';
 
@@ -14,4 +14,14 @@ export class CollectionsEndpoint extends BaseEndpoint {
     return await this.api.get<DetailedCollection>(`${BASE_COLLECTION}/${id}?${params}`);
   }
 
+  async images(id: number, options? : LanguageOption): Promise<ImageCollection> {
+    const params = querystring.encode(options);
+    return await this.api.get<ImageCollection>(`${BASE_COLLECTION}/${id}/images?${params}`);
+  }
+
+  async translations(id: number, options? : LanguageOption): Promise<Translations> {
+    const params = querystring.encode(options);
+    return await this.api.get<Translations>(`${BASE_COLLECTION}/${id}/translations?${params}`);
+  }
+
 }