Add solutions

Author: parthsarin

res/labs.json

@@ -4,8 +4,8 @@
         "topic": "Data Structures",
         "part1": "https://github.com/stanfordpython/python-labs/blob/master/notebooks/lab-2/data-structures-part-1.ipynb",
         "part2": "https://github.com/stanfordpython/python-labs/blob/master/notebooks/lab-2/data-structures-part-2.ipynb",
-        "solutions": "#",
+        "solutions": "https://github.com/stanfordpython/python-labs/blob/master/solutions/lab-2.py",
         "visible": true,
         "active": true
     }
-]
+]