DOC: config: retry-on list is space-delimited

DOC: config: retry-on list is space-delimited

We are using comma-delimited list for init-addr for example, let's
document that this is space-delimited to avoid the guessing game.

(cherry picked from commit de16008c298d87b212807b9bb42d27f675be732b)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit d9a0d71290259e4502bf44d7e246a6acc516ddb1)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit bb474ff83b557944ef1d5715dfa9c8fafeae444c)
Signed-off-by: Willy Tarreau <w@1wt.eu>