most POH don't specify angle limits for sloping ground. we are taught by the instructors 'to the limit of the cyclic controls', meaning that you need to be able to keep the rotor disc horizontal while the skids settle on the sloping ground, without 'bottoming out' the cyclic, if that makes sense.
also, it's different angles based on the orientation of the helicopter in relation to the slope direction, you get less degrees when slope is downwards, obviously your tail rotor would hit before any other issues (it is quite inadvisable to land tail rotor uphill, just pointing it out for the sake of discussion).
for contrast, the Mi8/Mi17 manual does state some angle limits, namely 7deg nose up and 5deg sideways, probably based on some other limits, CofG or wheel brake holding power, not familiar with why these precise limits, but this also considers the rotor mast built-in forward tilt when helicopter frame is horizontal. quite a different machine.
as a side note, sloping ground landings are part of the very basic helicopter handling syllabus, it's mandatory even for PPL level, it's taught right after being able to achieve a somewhat stable hover.