* Remove docs for the `asset_dir` variable and deprecate
it in CHANGES. It will be removed in an upcoming release
* Typhoon v1.17.0 introduced a new mechanism for managing
and distributing generated assets that stopped relying on
writing out to disk. `asset_dir` became optional and
defaulted to being unset / off (recommended)
* Add docs on manually uploading a Flatcar Linux GCE/GCP gzipped
tarball image as a Compute Engine image for use with the Typhoon
container-linux module
* Set status of Flatcar Linux on Google Cloud to alpha
* Add Typhoon Fedora CoreOS on Google Cloud as alpha
* Add docs on uploading the Fedora CoreOS GCP gzipped tarball to
Google Cloud storage to create a boot disk image