Add function for getting private game instances

[SirFireE]

It appears that Roblox has recently changed the way by which one gets server instances. Though it used to be the same endpoint for all types of servers, now there are two different endpoints. The old endpoint, "//games.roblox.com/v1/{placeId}/servers/{serverType}" has been updated to now require a number as the serverType parameter as shown on the docs. A new endpoint has also been added specifically for getting private server instances, which is "//games.roblox.com/v1/games/{placeId}/privateServers". I would appreciate it if a function was added just like getGameInstances to fetch private server instances. I apologize if I have not formatted this request correctly, it is my first time doing so.