docs: consolidate storage interfaces

to make the page more organized as requested

Signed-off-by: Costa Shulyupin <costa.shul@redhat.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20230618062937.481280-1-costa.shul@redhat.com