update announcement for release 1.6
update announcement for release 1.6

RussellSpitzer/snakeyaml,votinhthieugia/snakeyaml,yeison/snakeyaml,jeremypepper/snakeyaml,yskumar007/snakeyaml,nxbdi/snakeyaml,ldh0826/snakeyaml,thinkofdeath/snakeyaml,yishenggudou/snakeyaml,ilantoren/snakeyaml,UcasRichard/snakeyaml,Akkrite/snakeyaml,youxinren/snakeyaml,Fighter777/snakeyaml,mc-nekoneko/snakeyaml,SorinS/snakeyaml,marcuskara/snakeyaml,Mause/snakeyaml,virustotalop/snakeyaml,umeding/snakeyaml,mapiman/snakeyaml,joy32812/snakeyaml,AssafMashiah/assafmashiah-yaml,cuizhennan/snakeyaml