add pdnsutil note about attodot removal to upgrade guide

diff --git a/docs/upgrading.rst b/docs/upgrading.rst
index 9387cc9711ed4853aa1bb2c4b7b36080aa088f75..93e31abb62050edd873aef81dcdc7ea462f4bf63 100644 (file)
--- a/docs/upgrading.rst
+++ b/docs/upgrading.rst
@@ -19,6 +19,7 @@ However, this feature interacts badly with handling of presigned zones.
 In version 4.5.0, this feature was accidentally broken in the implementation of the zone cache.
 In 4.6.0, this automatic conversion is fully removed.
 If you still have ``@`` signs in any SOA RNAMEs, 4.6.0 will serve those out literally.
+You can find any stray ``@`` signs by running ``pdnsutil check-all-zones``.
 
 4.4.x to 4.5.0
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