Add link to homework

Author: encukou

runs/2020/brno-podzim-pondeli/info.yml

@@ -87,7 +87,7 @@ plan:
     url: https://pyvec.github.io/cheatsheets/strings/strings-cs.pdf
     type: cheatsheet
   - title: "Úkol (|‾)"
-    url: null
+    url: https://projekty.pyladies.cz/session?course=pyladies-2020-brno-podzim-pondeli&session=str
 
 
 - slug: def