restore "good" v8 imfile doc and some improvements
restore "good" v8 imfile doc and some improvements

This complete restauration of the lost-during-import content.
Also made things a bit more consistent and added some info.

teifler/rsyslog-doc,volter/rsyslog-doc,sematext/rsyslog-doc,qha/rsyslog-doc,qha/rsyslog-doc,rcuza/rsyslog-doc,taotetek/rsyslog-doc,rcuza/rsyslog-doc,teifler/rsyslog-doc,Whissi/rsyslog-doc,volter/rsyslog-doc,luozhihui/rsyslog-doc,mbiebl/rsyslog-doc,jite/rsyslog-doc,sematext/rsyslog-doc,qha/rsyslog-doc,janmejay/rsyslog-doc,rcuza/rsyslog-doc,sematext/rsyslog-doc,luozhihui/rsyslog-doc,ribeiropaulor/rsyslog-doc,qha/rsyslog-doc,rcuza/rsyslog-doc,jite/rsyslog-doc,sematext/rsyslog-doc,taotetek/rsyslog-doc,taotetek/rsyslog-doc,mbiebl/rsyslog-doc,ribeiropaulor/rsyslog-doc,janmejay/rsyslog-doc,luozhihui/rsyslog-doc,teifler/rsyslog-doc,taotetek/rsyslog-doc,volter/rsyslog-doc,ribeiropaulor/rsyslog-doc,jite/rsyslog-doc,ribeiropaulor/rsyslog-doc,volter/rsyslog-doc,janmejay/rsyslog-doc,Whissi/rsyslog-doc,mbiebl/rsyslog-doc,janmejay/rsyslog-doc,teifler/rsyslog-doc,Whissi/rsyslog-doc,luozhihui/rsyslog-doc,Whissi/rsyslog-doc,jite/rsyslog-doc