The keyword specifies how option works when specified multiple times:
- single: the last provided value replaces the earlier ones
- append: it supports being provided multiple times
- boolean: on/off values
- mutex: flag-like option that disable anoter flag
The 'gen.pl' script then outputs the proper and unified language for
each option's multi-use behavior in the generated man page.
The multi: header is requires in each .d file and will cause build error
if missing or set to an unknown value.
Closes#9759
gen.pl now generates a warning if the "See Also" field is not filled in for a
command line option
All command line options now provide one or more related options. 167
"See alsos" added!
Closes#8019