Install guide: fix rsync service startup

Document how the rsync service can be started for all distros.

Use "service" instead of "daemon", with associated markup.

Change-Id: I48a4760e2a11d5bc0301b77bda0fce5533c79021
Closes-Bug: #1274054
backport: havana
(cherry picked from commit 76f272a07d7dd7d5705c2e84ab5c341afd004755)