Update CHANGELOG.md for 0.15.0 (#4803)
Update CHANGELOG.md for 0.15.0 (#4803)

* Update CHANGELOG.md for 0.15.0

* mention #4575 in CHANGELOG.md

stweil/letsencrypt,jsha/letsencrypt,jsha/letsencrypt,lmcro/letsencrypt,lmcro/letsencrypt,letsencrypt/letsencrypt,letsencrypt/letsencrypt,stweil/letsencrypt