added Collection endpoint and types, buildable option interfaces

src/endpoints/collections.ts

@@ -0,0 +1,17 @@
+import { DetailedCollection, LanguageOption, PageOption } from '../types';
+import {  BaseEndpoint } from './base';
+import querystring from 'querystring';
+
+const BASE_COLLECTION = '/collection';
+
+export class CollectionsEndpoint extends BaseEndpoint {
+  constructor(protected readonly accessToken: string) {
+    super(accessToken);
+  }
+
+  async details(id: number, options? : LanguageOption): Promise<DetailedCollection> {
+    const params = querystring.encode(options);
+    return await this.api.get<DetailedCollection>(`${BASE_COLLECTION}/${id}?${params}`);
+  }
+
+}

src/endpoints/index.ts

@@ -15,4 +15,5 @@ export * from './review';
 export * from './trending';
 export * from './find';
 export * from './keywords';
+export * from './collections';