man: formatting fixes for literals

1. Literal values (like yes, no, on, off etc.)
should be typeset in bold not italic.

2. In simple cases like "--option yes | no" there
should be spaces around vertical pipe.

3. Square brackets (meaning "optional") should not be typeset in bold.

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
2 files changed