When the 'cpupower' utility installed in the custom dir, it fails to
render appropriate help info for a particular subcommand:
$ LD_LIBRARY_PATH=lib64/ bin/cpupower help monitor
with error message like 'No manual entry for cpupower-monitor.1'
The issue is that under the hood it calls 'exec' function with
the following args: 'man cpupower-monitor.1'. In turn, 'man' search
path is defined in '/etc/manpath.config'. Of course it contains only
standard system man paths.
Make subcommands help available for a user by setting up 'MANPATH'
environment variable to the custom installation man pages dir. That
variable value will be prepended to the man pages standard search paths
as described in 'SEARCH PATH' section of MANPATH(5).