DOC: management: change reference to configuration manual

Since e24b77e ('DOC: config: move the extraneous sections out of the
"global" definition') the ACME section of the configuration manual was
move from 3.13 to 12.8.

Change the reference to that section in "acme renew".

Author: wlallemand

doc/management.txt

@@ -1653,8 +1653,8 @@ abort ssl crl-file <crlfile>
 
 acme renew <certificate>
   Starts an ACME certificate generation task with the given certificate name.
-  The certificate must be linked to an acme section, see section 3.13. of the
-  configuration manual. See also "acme status".
+  The certificate must be linked to an acme section, see section 12.8 "ACME"
+  of the configuration manual. See also "acme status".
 
 acme status
   Show the status of every certificates that were configured with ACME.