Add / Cancel order inconsistency

Stream: general

[Junyan Xu]

docs#AddCancelMonoid
docs#AddCancelCommMonoid
docs#AddLeftCancelMonoid
docs#AddLeftCancelSemigroup
etc. vs.
docs#OrderedCancelAddCommMonoid
docs#LinearOrderedCancelAddCommMonoid
Probably less work to change the latter two (anything else I missed)?

[Yaël Dillies]

We already had a similar conversation with the effect that comm_cancel_monoid became cancel_comm_monoid, I believe.