Remove broken link to PhutilHighIntensityIntervalDaemon docs

Summary: Closes T15845

Test Plan: Read the code - this changes nothing other than comments

Reviewers: O1 Blessed Committers, aklapper

Reviewed By: O1 Blessed Committers, aklapper

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

Maniphest Tasks: T15845

Differential Revision: https://we.phorge.it/D25680