doc/radosgw: refine "Zones" in multisite.rst

Describe in greater detail the function of Zones in serving S3 objects,
as requested by Alexander Patrakov here:
https://github.com/ceph/ceph/pull/49981#issuecomment-1615866374.

Signed-off-by: Zac Dover <zac.dover@proton.me>
(cherry picked from commit 8dab6c066c4dd3699c7b7c80f7a30a0e18326bba)

diff --git a/doc/radosgw/multisite.rst b/doc/radosgw/multisite.rst
index 471e85892d666968584d83afc72565106975671f..43d28b456636e6f452895dcbdcc095a853819377 100644 (file)
--- a/doc/radosgw/multisite.rst
+++ b/doc/radosgw/multisite.rst
@@ -1344,7 +1344,7 @@ Zones
 -----
 
 A zone defines a logical group that consists of one or more Ceph Object Gateway
-instances. Ceph Object Gateway supports zones.
+instances. All RGWs in a given zone serve S3 objects that are backed by RADOS objects that are stored in the same set of pools in the same cluster. Ceph Object Gateway supports zones.
 
 The procedure for configuring zones differs from typical configuration
 procedures, because not all of the settings end up in a Ceph configuration