Reason1:
other runc manual are using word of "SYNOPSIS"
# grep USAGE man/*
# man/runc-checkpoint.8.md:#USAGE
#
# grep SYNOPSIS man/*
man/runc-checkpoint.8.md:# SYNOPSIS
man/runc-delete.8.md:# SYNOPSIS
man/runc-events.8.md:# SYNOPSIS
man/runc-exec.8.md:# SYNOPSIS
man/runc-kill.8.md:# SYNOPSIS
man/runc-list.8.md:# SYNOPSIS
man/runc-pause.8.md:# SYNOPSIS
man/runc-restore.8.md:# SYNOPSIS
man/runc-resume.8.md:# SYNOPSIS
man/runc-spec.8.md:# SYNOPSIS
man/runc-start.8.md:# SYNOPSIS
man/runc-state.8.md:# SYNOPSIS
man/runc-update.8.md:# SYNOPSIS
man/runc.8.md:# SYNOPSIS
#
Reason2:
Most linux commands are using word of "SYNOPSIS"
# man ls
# man find
# ...
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>