[DOCS] Clarify certgen deprecation (elastic/x-pack-elasticsearch#4099)
Original commit: elastic/x-pack-elasticsearch@819f0ecf082fb41c5dd921fb335280bd8c93fd34
@@ -6,7 +6,8 @@ deprecated[6.1,Replaced by <<certutil,`certutil`>>. ]
The `certgen` command simplifies the creation of certificate authorities (CA),
certificate signing requests (CSR), and signed certificates for use with the
-Elastic Stack.
+Elastic Stack. Though this command is deprecated, you do not need to replace CA,
+CSR, or certificates that it created.
[float]
=== Synopsis
