doc: framework for documenting standard macro packages
doc: framework for documenting standard macro packages

Add a framework for documenting the standard macro packages.  Also
move the standard macros to the end of the preprocessor section,
instead of having them in the middle of the directives list.

techkey/nasm,turingstudio/nasm,projedi/nasm,turingstudio/nasm,Distrotech/nasm,techkey/nasm,letolabs/nasm,Distrotech/nasm,techkey/nasm,turingstudio/nasm,Distrotech/nasm,techkey/nasm,techkey/nasm,projedi/nasm,letolabs/nasm,Distrotech/nasm,letolabs/nasm,projedi/nasm,projedi/nasm,turingstudio/nasm,projedi/nasm