scsi: fc_transport: docs: Add documentation for FC Remote Ports

scsi: fc_transport: docs: Add documentation for FC Remote Ports

This patch updates the scsi_fc_transport.rst documentation by replacing
the outdated << To Be Supplied >> placeholder under the "FC Remote Ports
(rports)" section with a detailed explanation of remote port
functionality in the Fibre Channel (FC) transport class.

The new documentation covers:

 - What rports are and their role in FC-based SCSI communication

 - Their representation in sysfs (/sys/class/fc_remote_ports/)

 - Common sysfs attributes such as (port_id, port_name, node_name, and
   port_state).

 - Their typical lifecycle (creation and removal)

 - Guidance for driver developers on using fc_remote_port_add() and
   fc_remote_port_delete()

This change improves the completeness and usefulness of the FC transport
documentation for developers and users interacting with Fibre Channel
drivers in the Linux SCSI subsystem

Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>
Link: https://lore.kernel.org/r/20250607162304.1765430-1-alok.a.tiwari@oracle.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>