Clarify that synced segment container names must be the same
when syncing large objects.
Also add multipart-menifest query string option to API ref
for object GETs.
Change-Id: Ib2d2a1e6c1e5eff215fc75c2b49e7d6758b17b7e
Partial-Bug: #1613681
Closes-Bug: #1613316