doc: fix broken link to global directive doc
bugfix: immark did emit messages under kern.=info instead of syslog.=info

Note that his can potentially break exisiting configurations that
rely on immark sending as kern.=info. Unfortunately, we cannot leave
this unfixed as we never should emit messages under the kern facility.
Merge branch 'v7-stable' into v7-devel

Conflicts:
	ChangeLog
	doc/rainerscript.html
Merge branch 'v7-devel'
Merge branch 'master' of https://github.com/rsyslog/rsyslog