I don’t find anymore the official blizzard StarCraft II guide/manual with detailed description of each unit, building, etc. Could you give me the link to this website ?
The unit details and such was not transfered from the old site when they updated it, the closest thing to that would be the one mostly preserved on IGN or on the user made wiki on FANDOM.
Beside that you can access some of the descriptions in game by opening the menu with ESC, click HELP and check the respective Void Multiplayer sections.