umass.4: Modernize driver loading instructions

+ consolidate kernel configuration in SYNOPSIS
+ explain driver autoloading in DESCRIPTION
+ s/port/interface/ because of internal USBs
+ fix flow of remaining example

MFC after:	1 day

share/man/man4/umass.4

@@ -25,44 +25,44 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd October 2, 2025
+.Dd October 9, 2025
 .Dt UMASS 4
 .Os
 .Sh NAME
 .Nm umass
 .Nd USB Mass Storage Devices driver
 .Sh SYNOPSIS
-To compile this driver into the kernel,
-place the following line in your
-kernel configuration file:
-.Bd -ragged -offset indent
+.Cd "device da"
 .Cd "device scbus"
+.Cd "device pass"
 .Cd "device usb"
 .Cd "device umass"
-.Ed
 .Pp
-Alternatively, to load the driver as a
-module at boot time, place the following line in
+In
 .Xr loader.conf 5 :
-.Bd -literal -offset indent
-umass_load="YES"
-.Ed
+.Cd umass_load
 .Sh DESCRIPTION
 The
 .Nm
 driver provides support for Mass Storage devices that attach to the USB
-port.
+interface.
 .Pp
-To use the
-.Nm
-driver,
+If the appropriate hardware is detected,
+the driver will be loaded automatically by
+.Xr devmatch 8 .
+To load the driver manually at boot time, use the
+.Cm umass_load
+command at the
+.Xr loader 8
+prompt, or add it to
+.Xr loader.conf 5 .
+.Pp
+To use the driver in a custom kernel,
 .Xr usb 4
-and one of
-.Xr uhci 4
-or
-.Xr ohci 4
-or
-.Xr ehci 4
+and at least one of
+.Xr uhci 4 ,
+.Xr ohci 4 ,
+.Xr ehci 4 ,
 or
 .Xr xhci 4
 must be configured in the kernel.
@@ -88,16 +88,8 @@ USB hard disk drives
 USB floppy drives
 .El
 .Sh EXAMPLES
-.Bd -literal -offset indent
-device umass
-device scbus
-device da
-device pass
-.Ed
-.Pp
-Add the
-.Nm
-driver to the kernel.
+Rescan all slots on a multi-slot flash reader,
+where the slots map to separate LUNs on a single SCSI ID:
 .Bd -literal -offset indent
 camcontrol rescan 0:0:0
 camcontrol rescan 0:0:1
@@ -105,8 +97,6 @@ camcontrol rescan 0:0:2
 camcontrol rescan 0:0:3
 .Ed
 .Pp
-Rescan all slots on a multi-slot flash reader, where the slots map to separate
-LUNs on a single SCSI ID.
 Typically only the first slot will be enabled at boot time.
 This assumes that
 the flash reader is the first SCSI bus in the system and has 4 slots.