Add 1.2 -> 2.0 migration guide
Add 1.2 -> 2.0 migration guide

pferreir/indico,DirkHoffmann/indico,ThiefMaster/indico,ThiefMaster/indico,DirkHoffmann/indico,indico/indico,OmeGak/indico,DirkHoffmann/indico,mvidalgarcia/indico,indico/indico,pferreir/indico,OmeGak/indico,mic4ael/indico,mic4ael/indico,OmeGak/indico,DirkHoffmann/indico,mic4ael/indico,OmeGak/indico,indico/indico,indico/indico,mvidalgarcia/indico,pferreir/indico,pferreir/indico,mvidalgarcia/indico,ThiefMaster/indico,mic4ael/indico,mvidalgarcia/indico,ThiefMaster/indico