This revises that compute node release note to describe the SIGHUP
service behavior impacts.
Related to blueprint service-version-behavior
Change-Id: I5030cba5e12d3cdfbb563258358c2e43e66bcc08
Change I679ebedb739a487e2e4e811c4e89b9c07c8b99bc added a new 'auto' value
for upgrade_levels.compute
Change-Id: I21f2678ab4f68cddb7f76c5c8f9c7b0d878e705a