docs: improve pg_upgrade rsync instructions

Bruce Momjian <bruce@momjian.us>

Commit: b1705f35f805933629520eded68b82d2a2900871
Author: Bruce Momjian <bruce@momjian.us>
Date: 2017-09-12T17:17:52Z
Releases: 10.0
docs:  improve pg_upgrade rsync instructions

This explains how rsync accomplishes updating standby servers and
clarifies the instructions.

Reported-by: Andreas Joseph Krogh

Discussion: https://postgr.es/m/VisenaEmail.10.2b4049e43870bd16.15d898d696f@tc7-visena

Backpatch-through: 9.5

Files

PathChange+/−
doc/src/sgml/ref/pgupgrade.sgml modified +24 −16

Documentation touched