The new GL markdown reference syntax uses the extensible format.

Iterations cadence can be referenced by either its title or id:

[cadence:<ID>] or [cadence:"title"].

The new reference type is only intended to be parsed
as part of the iterations quick action command.
In other words, iterations cadence references will NOT be rendered to HTML.

Changelog: added
EE: true

Add reference class to cadence parser

Update cadence spec