Update output language options to the latest (#61)

Reference:
- https://kagi.com/summarizer/index.html

shared/src/popup.html

@@ -197,6 +197,7 @@
             <label for="target_language">Output Language</label>
             <select id="target_language">
               <option value="" selected="selected">Default</option>
+              <option value="DOC">Document Language</option>
               <option value="BG">Bulgarian</option>
               <option value="CS">Czech</option>
               <option value="DA">Danish</option>
@@ -226,6 +227,7 @@
               <option value="TR">Turkish</option>
               <option value="UK">Ukrainian</option>
               <option value="ZH">Chinese (simplified)</option>
+              <option value="ZH-HANT">Chinese (traditional)</option>
             </select>
           </div>