docs: Move Intel Many Integrated Core documentation (mic) under misc-devices

It doesn't need to be a top-level chapter.

This patch also updates MAINTAINERS and makes sure the F: lines are
properly sorted.

Signed-off-by: Jonathan Neuschäfer <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/index.rst

···
    usb/index
    PCI/index
    misc-devices/index
-   mic/index
    scheduler/index
 
 Architecture-agnostic documentation

Documentation/misc-devices/index.rst

···
    isl29003
    lis3lv02d
    max6875
+   mic/index
    xilinx_sdfec

MAINTAINERS

···
 S:	Supported
 W:	https://github.com/sudeepdutt/mic
 W:	http://software.intel.com/en-us/mic-developer
+F:	Documentation/misc-devices/mic/
+F:	drivers/dma/mic_x100_dma.c
+F:	drivers/dma/mic_x100_dma.h
+F:	drivers/misc/mic/
 F:	include/linux/mic_bus.h
 F:	include/linux/scif.h
 F:	include/uapi/linux/mic_common.h
 F:	include/uapi/linux/mic_ioctl.h
 F:	include/uapi/linux/scif_ioctl.h
-F:	drivers/misc/mic/
-F:	drivers/dma/mic_x100_dma.c
-F:	drivers/dma/mic_x100_dma.h
-F:	Documentation/mic/
 
 INTEL PMC CORE DRIVER
 M:	Rajneesh Bhardwaj <[e-mail]>