Mention at_exit handler in CHANGELOG.md
Mention at_exit handler in CHANGELOG.md

Seikitsu/gooddata-ruby,fluke777/gooddata-ruby,fluke777/gooddata-ruby,Seikitsu/gooddata-ruby,vhtien/gooddata-ruby,Seikitsu/gooddata-ruby,vhtien/gooddata-ruby,fluke777/gooddata-ruby,lubosvesely/gooddata-ruby,vhtien/gooddata-ruby,lubosvesely/gooddata-ruby,lubosvesely/gooddata-ruby