Container documentation

[wvpm]

Documentation describing the various C++ types used to store items.
Use this to pick between container types.

[schombert]

Do you have tests for this type?

	inline constexpr cow_vector<T, Allocator>::size_type cow_vector<T, Allocator>::payload::content_size =
		std::max<size_type>(1ul, (sizeof(payload) - sizeof(array)) / sizeof(T));

would cause the first member of the array to overlap the pointer to the array itself for some sizes of T. If you were trying to have it round up to the largest number of T sufficient to contain the non-T payload data, it would be = (sizeof(payload) + sizeof(T) - 1) / sizeof(T)