With World of Warcraft beta build 18505 online, the Garrison buildings (Large & Medium) have gotten an upgrade tooltip overhaul from level 1-3. I have updated our Garrison Guide to reflect these changes.
Specializations seem to be gone, but I am unsure if that’s permanent. I have left the specializations unedited for now — so simply ignore those areas. Focus your reading on the Level 1-3 upgrades. Small Building upgrades haven’t been touched in this beta build.