For those who weren't around on Heavenswards launch:

The "Preliminary Patch Notes" are released a few days before the servers go down and are a heavily redacted version of the full patch notes that try to contain no advantageous information.

The "Full Patch Notes" are released after the servers go down and contain all of the market board destroying information. These patch notes are read live by Yoshi P a few hours before maintenance ends. However, for Heavenswards release they said "There are too many new items to list and therefore new items and recipes will not be included in the full patch notes." So please do not look forward to that in particular.