PCI: Update documentation 00-INDEX file

The PCI-DMA-mapping.txt moved to general docs and became DMA-API-HOWTO.txt
in 5e07c2c ("Documentation: rename PCI/PCI-DMA-mapping.txt to
DMA-API-HOWTO.txt").  Add new file about PCI Express I/O Virtualization.

Signed-off-by: Erik Ekman <erik@kryo.se>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Documentation/PCI/00-INDEX

@@ -2,12 +2,12 @@
 	- this file
 MSI-HOWTO.txt
 	- the Message Signaled Interrupts (MSI) Driver Guide HOWTO and FAQ.
-PCI-DMA-mapping.txt
-	- info for PCI drivers using DMA portably across all platforms
 PCIEBUS-HOWTO.txt
 	- a guide describing the PCI Express Port Bus driver
 pci-error-recovery.txt
 	- info on PCI error recovery
+pci-iov-howto.txt
+	- the PCI Express I/O Virtualization HOWTO
 pci.txt
 	- info on the PCI subsystem for device driver authors
 pcieaer-howto.txt