Merge branch 'master' into config-fixup

internal/run/upgrade.go

@@ -25,6 +25,8 @@ func (u *Upgrade) Execute(_ Config) error {
 }
 
 // Prepare gets the Upgrade ready to execute.
+// Note: mandatory settings are documented in README.md, and the full list of settings is in docs/upgrade_settings.yml.
+// Any additions or deletions here should be reflected there.
 func (u *Upgrade) Prepare(cfg Config) error {
 	if u.Chart == "" {
 		return fmt.Errorf("chart is required")