Document the maintenance points

[paulgazz]

• The list of architectures to try, which is in https://github.com/paulgazz/kmax/blob/master/kmax/arch.py#L55 Perhaps klocalizer could check the arch/ directory for any additions, although some architectures have different arch vs. src_arch, i.e., the name of the architecture vs. the path, e.g., x86/ is used for both x86_64 and i386.
• The kconfig grammar, which is in https://github.com/paulgazz/kmax/tree/master/kextractors These are the parsers from the original kconfig tool, for each version where we noticed a change in parsing.
• The built-in kbuild path rewrites (see Add support for automatic kbuild path rewriting #196 )