Document the hunters and the new way that iteration works.

Signed-off-by: Simon Glass <sjg@chromium.org>

Apple SoCs have an integrated NVMe controller that isn't connected
over a PCIe bus. In preparation for adding support for this NVMe
controller, split out the PCI support into its own file. This file
is selected through a new CONFIG_NVME_PCI Kconfig option, so do
a wholesale replacement of CONFIG_NVME with CONFIG_NVME_PCI.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested on: Macbook Air M1
Tested-by: Simon Glass <sjg@chromium.org>

This converts the existing README.nvme to reST, and puts it under
the develop/driver-model/ directory.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>