This is more consistent with other parameters and conforms to
the pattern used by PostgreSQL itself, which uses the prefix "log_"
for logging parameters.
A warning will be emitted if the old version of the parameter name
is detected.
Normally (outside of log level DEBUG) repmgrd doesn't generate any
kind of log output, so examining the log file may give the impression
it's not working. Output an informational message at regular intervals
to show it's up and running.
This is more consistent with other parameters and conforms to
the pattern used by PostgreSQL itself, which uses the prefix "log_"
for logging parameters.
A warning will be emitted if the old version of the parameter name
is detected.
