Update CHANGELOG.md for #509
Update CHANGELOG.md for #509

mattermost/desktop,mattermost/desktop,yuya-oc/desktop,mattermost/desktop,jnugh/desktop,yuya-oc/electron-mattermost,yuya-oc/desktop,mattermost/desktop,mattermost/desktop,jnugh/desktop,yuya-oc/electron-mattermost,yuya-oc/electron-mattermost,jnugh/desktop,yuya-oc/desktop