doc: show details of command options in pages generated by docutils
Before this patch, HTML/man pages generated by docutils don't show
details of each command options, whether it should take argument or
not for example, even though "hg help" does.
This patch shows details of command options as same as "hg help"
shows.
This patch uses "--option <VALUE[+]>" style instead of "--option
<VALUE> [+]" used in output of "hg help", because docutils requires
that option argument strings starts with "<" and ends with ">".