[DOC] Make the status listener example complete.

[DOC] Make the status listener example complete.

The example for configuration of "Status report in HTML page"
in haproxy-en.txt/haproxy-fr.txt is incomplete. Gives me the
below error, and had me scratching my head a bit :-)

[ALERT] 074/131807 (26359) : parsing /etc/haproxy/haproxy.cfg : listener
stats has no dispatch address and is not in transparent or balance mode.
[ALERT] 074/131807 (26359) : Errors found in configuration file, aborting.
[ALERT] 074/131807 (26359) : Error reading configuration file :
/etc/haproxy/haproxy.cfg

If adding "balance roundrobin" to the stats stanza is the right fix,
please apply the attached documentation patch to haproxy v1.2 and v1.3.

[w@1wt.eu: this is the right fix up to 1.3.15, not needed in 1.3.16]
(cherry picked from commit dad07a861200d84f68c19de7e84f775b2a0e6cbb)