kernel-doc: warn on badly formatted short description

kernel-doc: warn on badly formatted short description

Make kernel-doc warn when a function/struct/union/typedef does not contain
a properly formatted short description, such as:
 * scsi_devinfo: set up the dynamic device list
or
 * scsi_devinfo -

This warning is only generated when verbose (-v) mode is used.

Also explain the -v command line option in the -h output.

Signed-off-by: Randy Dunlap <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>