coco3: Build SD card device descriptors for CoCo3FPGA Added "CC3FPGAFLAGS = $(AFLAGS) -DCC3FPGA=1 $(FLAGS)" to "level2/coco3/modules/makefile" for flagging Coco3FPGA specific features in modules sources. Added "llcoco3fpga", "ddsd0_coco3fpga", "sd0_coco3fpga", and "sd1_coco3fpga" to the "coco3/modules/makefile" - RBF section, which also now adds all to the "NITROS9/MODULES/RBF" on all disk images for building new Coco3FPGA disks from NitrOS9. Added new descriptor section to the "level2/coco3/modules/makefile" reflecting the new Coco3FPGA SD card descriptors and their flags.

About "See Also" references:
    In the reference entries there are a lot of references to other
    function calls. They should according to DocBook be implemented with
    the <function>-element, but this doesn't produce the desired result
    in my formatter. Instead the <link>-element has been used. In the
    future when a better formatter is available, you can replace
	<link linkend="creat">creat()</link>,
    with
	<function moreinfo="refentry">creat</function>,