Add changelog for release v0.1.0 (grafana#81)

* Add changelog for release v0.1.0

* Latest changes, and mention feature flag

* Update CHANGELOG.md

Co-authored-by: Jeroen Op 't Eynde <[email protected]>

* Change release date

Co-authored-by: Jeroen Op 't Eynde <[email protected]>

Merge pull request grafana#33 from grafana/second-attempt-at-removing…

…-drone-link

Remove drone link, second time