doc: release notes for 7.4
doc: release notes for 7.4

bansalayush/checkstyle,sharang108/checkstyle,checkstyle/checkstyle,sirdis/checkstyle,romani/checkstyle,checkstyle/checkstyle,romani/checkstyle,romani/checkstyle,jochenvdv/checkstyle,rnveach/checkstyle,MEZk/checkstyle,AkshitaKukreja30/checkstyle,izishared/checkstyle,checkstyle/checkstyle,jonmbake/checkstyle,jonmbake/checkstyle,AkshitaKukreja30/checkstyle,sharang108/checkstyle,checkstyle/checkstyle,sirdis/checkstyle,izishared/checkstyle,MEZk/checkstyle,bansalayush/checkstyle,jochenvdv/checkstyle,romani/checkstyle,checkstyle/checkstyle,nikhilgupta23/checkstyle,jochenvdv/checkstyle,liscju/checkstyle,romani/checkstyle,liscju/checkstyle,checkstyle/checkstyle,rnveach/checkstyle,MEZk/checkstyle,rnveach/checkstyle,ilanKeshet/checkstyle,romani/checkstyle,rnveach/checkstyle,nikhilgupta23/checkstyle,jonmbake/checkstyle,sirdis/checkstyle,nikhilgupta23/checkstyle,AkshitaKukreja30/checkstyle,sabaka/checkstyle,liscju/checkstyle,rnveach/checkstyle,bansalayush/checkstyle,ilanKeshet/checkstyle,sharang108/checkstyle,sabaka/checkstyle,rnveach/checkstyle,izishared/checkstyle,sabaka/checkstyle,ilanKeshet/checkstyle