dbupdater: add mysql transaction warning

css/tt-rss.less

@@ -1141,6 +1141,10 @@ body.ttrss_main, body.ttrss_utility {
 		color: #468847;
 	}
 
+	.text-warning {
+		color: darken(#c09853, 10%);
+	}
+
 	.alert,
 	.alert h4 {
 		color: #c09853;