manpage: modify OPTIONS to FLAGS

[Mashimiao]

Signed-off-by: Ma Shimiao mashimiao.fnst@cn.fujitsu.com

[xiekeyang]

I think change from flag to option is OK, but this should be accordant to tools usage.

[Mashimiao]

I think the change does not make manpage to be not accordant with tools usage.

[xiekeyang]

I mean help message of tools had better to be changed accordingly(flag to option), to be like

$ ./oci-image-validate --help
Usage:  oci-image-validate FILE... [options...]
Options: ...

[Mashimiao]

Though I want to change all of flags to options which I think is more common. But as cobra use flags instead of options as default, it seems better to change OPTIONS to FLAGS in manpage. @xiekeyang PTAL

[xiekeyang]

LGTM

[vbatts]

LGTM