Fix a bad %d for PHID

Summary: D1174 caught this issue -- we mean to load all your rules, but
actually load all rules. Use %s correctly.

Test Plan: Hit /herald/rule/ without an exception.

Reviewers: fmoo, btrahan, jungejason

Reviewed By: btrahan

CC: aran, epriestley, btrahan

Differential Revision: 1203