Dev: doc/man: Clean up ShellCheck warnings
In ./doc/man/mkappendix.sh line 10:
for manpage in printf "%s\n" $@ | sort -f; do
^-- SC2006: Use $(..) instead of legacy `..`.
^-- SC2068: Double quote array expansions to avoid re-splitting elements.In ./doc/man/ralist.sh line 7:
for f in find $RADIR -type f -executable; do
^-- SC2044: For loops over find output are fragile. Use find -exec or a while read loop.
^-- SC2006: Use $(..) instead of legacy `..`.
^-- SC2086: Double quote to prevent globbing and word splitting.