Update harep's man page to notify users of its limitations
Update harep's man page to notify users of its limitations

In particular that it works only for 'drbd' and 'plain', and that it
doesn't perform hardware failure detection, which are both common user
expectations.

Signed-off-by: Petr Pudlak <9d19625f8ee825a2c398462ed335cbcf98f79c32@google.com>
Reviewed-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>

yiannist/ganeti,leshchevds/ganeti,yiannist/ganeti,andir/ganeti,mbakke/ganeti,ganeti/ganeti,ganeti/ganeti,onponomarev/ganeti,ganeti/ganeti,mbakke/ganeti,andir/ganeti,mbakke/ganeti,andir/ganeti,leshchevds/ganeti,yiannist/ganeti,leshchevds/ganeti,onponomarev/ganeti