Update README with some building instructions
Update README with some building instructions

gausie/opal,suyesh/opal,Ajedi32/opal,Flikofbluelight747/opal,jannishuebl/opal,fazibear/opal,wied03/opal,iliabylich/opal,iliabylich/opal,kachick/opal,castwide/opal,kachick/opal,Flikofbluelight747/opal,bbatsov/opal,c42engineering/opal,kachick/opal,Mogztter/opal,opal/opal,gabrielrios/opal,c42engineering/opal,opal/opal,opal/opal,suyesh/opal,catprintlabs/opal,suyesh/opal,gabrielrios/opal,charliesome/opal,fazibear/opal,domgetter/opal,wied03/opal,Mogztter/opal,Mogztter/opal,merongivian/opal,wied03/opal,catprintlabs/opal,merongivian/opal,gausie/opal,bbatsov/opal,gabrielrios/opal,bbatsov/opal,jannishuebl/opal,catprintlabs/opal,fazibear/opal,Flikofbluelight747/opal,jannishuebl/opal,Ajedi32/opal,jgaskins/opal,merongivian/opal,castwide/opal,jgaskins/opal,Mogztter/opal,charliesome/opal,Ajedi32/opal,opal/opal,castwide/opal,iliabylich/opal,kachick/opal,domgetter/opal,c42engineering/opal,jgaskins/opal,gausie/opal