A bunch of volume APIs are missing in current documentation, such
as os-reserve/os-unreserve/os-begin_detaching/os-roll_detaching
os-initialize_connection/os-terminate_connection, this patch is aim to
add the missing APIs.
Change-Id: If0732aa94db4e8cdef30a2be0c53314b507ee002
Closes-bug: #1761049