Add missing closing double-quote on PreviewsHost

config.go

@@ -22,7 +22,7 @@ type config struct {
 
 	AutoApprove  bool   `env:"key=AUTO_APPROVE default=false"`
 	AllowPublish bool   `env:"key=ALLOW_PUBLISH default=true"`
-	PreviewsHost string `env:"key=PREVIEWS_HOST`
+	PreviewsHost string `env:"key=PREVIEWS_HOST"`
 	AdminPass    string `env:"key=ADMIN_PASS default=uhoh"`
 	BrowseItems  int    `env:"key=BROWSE_ITEMS default=10"`