Correct a mistaken Phurl link in the "missing symbol" exception
Correct a mistaken Phurl link in the "missing symbol" exception

Summary: See PHI2022. This link is missing the `/u/` part and currently 404's.

Test Plan: Followed the new link, got documentation.

Differential Revision: https://secure.phabricator.com/D21611

Khan/arcanist,phacility/arcanist,phacility/arcanist,codelabs-ch/arcanist,phacility/arcanist,Khan/arcanist,codelabs-ch/arcanist,Khan/arcanist,Khan/arcanist,codelabs-ch/arcanist,phacility/arcanist,codelabs-ch/arcanist,phacility/arcanist,codelabs-ch/arcanist