[FIX] project: description_pad field holds the pad URL; udpated

the string to be less error-prone.

addons/pad_project/project_task.py

@@ -6,5 +6,5 @@ class task(osv.osv):
     _name = "project.task"
     _inherit = ["project.task",'pad.common']
     _columns = {
-        'description_pad': fields.char('Description PAD', pad_content_field='description')
+        'description_pad': fields.char('Pad URL', pad_content_field='description')
     }