pandoc required for creating man pages

[sharkcz]

There are distros like RHEL where pandoc is not available that will cause missing man pages there (or maybe a build failure even). Please see a workaround from the s390-tools project in ibm-s390-linux/s390-tools@0d15a07

[holger-dengler]

Ok, I'll provide a similar workaround for libzpc.