updated CHANGELOG.md

Signed-off-by: Miguel Ángel Ortuño <[email protected]>

v0.60.0 release (ortuman#233)

Signed-off-by: Miguel Ángel Ortuño <[email protected]>

v0.59.0 release (ortuman#219)

v0.58.0 release (ortuman#216)

v0.57.0 release (ortuman#210)

bump up application version number (ortuman#197)

Configuration refactoring (ortuman#182)

Minor fixes (ortuman#160)

Add support for XEP-0198: Stream Management (ortuman#158)

Update example.config.yaml