Fix phacility link for arcanist guides

Summary: Signed-off-by: Yongmin Hong <revi@pobox.com>

Test Plan: Checkout https://we.phorge.it/book/phorge/article/arcanist and https://we.phorge.it/book/phorge/article/arcanist_quick_start/ and verify the new clone URL.

Reviewers: O1 Blessed Committers, aklapper

Reviewed By: O1 Blessed Committers, aklapper

Subscribers: aklapper, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Differential Revision: https://we.phorge.it/D25573