The "path-to-tag" setting:
If the path-to-tag setting is defined and is not an empty string
then the /info page for checkin HASH will display a link to
a timeline showing an abbreviated path from the HASH checkin to
the next checkin that has a tag which is the value of this setting.
A typical value for this setting is "release", in which case a "path-to-release" link is shown on /info pages of checkins.