Add task link to 2026 Google Summer of Code details

Add task link to Paintroid advanced features idea.

Author: wslany

pages/development/google-summer-of-code/2026.md

@@ -93,7 +93,8 @@ The developer should have knowledge of Flutter. Develop and implement missing to
 > **Required Skills**: Flutter, Dart, Android-Development, Agile Development <br>
 > **Possible Mentors**: Julia Herold, Thorsten Bandel, Abdulbaki Celebi, Mario Kaurin <br>
 > **Expected Outcome**: Add antialiasing and smoothing as advanced options<br>
-> **Difficulty level**: Medium to advanced 
+> **Difficulty level**: Medium to advanced <br>
+> **Task link**: [View task](https://docs.google.com/document/d/1MdbFbf1AD6lbKqU0RmnKvPwWC8igXuwr9dD7UXMGwZA/edit?usp=sharing)
 
 The developer should have knowledge of Flutter. Develop and implement missing tools in Flutter that exist in our old Android app built with Android Native.