criu(8): fix typesetting

It's actually not very complicated. Just do this:

1 For literals (verbal text, such as command or option name) use *bold*

2 For substitutions (variable parameter name) use 'italic'

3 Do not use <angle brackets> at all.

Example:

	*-f* 'file'

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>