chore(release): Changelog for 0.15 stable (grafana#542)

* chore(release): Changelog for 0.15 stable

* style

* add one more PR

chore(release): Changelog for 0.14 stable (grafana#491)

chore(release): 0.13.0

chore(release): 0.12.0

chore(release): v0.12.0-alpha3

chore(release): v0.12-alpha3

chore(release): 0.12.0-alpha2

chore(release): 0.12.0-alpha1

chore(release): v0.11.1

chore(release): 0.11.0