scsi: documentation: Clean up overview

 - Change http to https where the latter works

 - Drop references to I2O (Intelligent I/O)

 - Use lore.kernel.org instead of marc.info for email links

 - Update the location of the scsi_debug documentation

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20240408025425.18778-3-rdunlap@infradead.org


Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>