6.9.0 6863/supp vers (#4100)
6.9.0 6863/supp vers (#4100)

* release notes update for 6.9.0-6863

* updated for 6.9.0 release

* Revert "release notes update for 6.9.0-6863"

This reverts commit 989bcf3b7704603540a6f543679c66ff2393e932.
sensu/sensu-docs,sensu/sensu-docs,sensu/sensu-docs,sensu/sensu-docs,sensu/sensu-docs