Update Rake man page [ci skip]

Verbatim copied from rake/doc/rake.1 @ v10.4.0

Follows 3908d5d3303dbd3f20f106aa71b5c094b67ac577 (r48560)
Resolves jimweirich/rake#283

Signed-off-by: Aleksandrs Ļedovskis <aleksandrs@ledovskis.lv>