docs: cleanup directory, fix some porting information

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+Some notes to help future porters.  Replace 'ARCH' with whatever arch
+you are hacking on.
+
+====================
+=== Config Files ===
+====================
+- create extra/Configs/Config.ARCH
+   See the other arch files for some good examples.  powerpc/sparc/alpha
+   should be pretty simple templates.
+- add ARCH to the 'Target Architecture' list in extra/Configs/Config.in
+- Initially you will want to disable shared libraries, since making
+   the shared library loader work requires you first have basic architecture
+   support working.  Thus you should add ARCH_HAS_NO_SHARED and
+   ARCH_HAS_NO_LDSO to Config.ARCH's TARGET_ARCH
+
+====================
+=== libc sysdeps ===
+====================
+(note: if glibc has already been ported to your arch, you can usually just
+       copy a lot of files from them rather than coding from scratch)
+- create libc/sysdeps/linux/ARCH
+- copy Makefile and Makefile.arch from libc/sysdeps/linux/i386/
+- set CSRC and SSRC to nothing in Makefile.arch for now
+
+- create crt1.S which defines the _start function ... you will probably want
+  to clear the frame pointer to make gdb happy, and then you will want to call
+  the funcion __uClibc_main() which takes these parameters:
+   __uClibc_main(main(), argc, argv, _init(), _fini())
+  Initially if you wish to make things easier on yourself, you can disable the
+  UCLIBC_CTOR_DTOR option and just set the init/fini arguments to NULL.
+  glibc generally stores this function in libc/sysdeps/ARCH/elf/start.S
+
+- create these additional files in ARCH/bits/
+
+  (template versions can be found in common/bits/ for you to tweak)
+  endian.h  fcntl.h  setjmp.h  stackinfo.h  uClibc_arch_features.h  wordsize.h
+
+  kernel_types.h should be created based upon linux asm-ARCH/posix_types.h
+
+  copy linux asm-ARCH/stat.h to bits/kernel_stat.h
+
+  create syscalls.h based upon linux's unistd.h / glibc's sysdeps.h ... really
+  you just want to define the _syscall[0-6] macros.  It is important that
+  these syscalls should be PIC safe (or you should provide a PIC and non-PIC
+  version) if you wish to properly support shared libraries.
+
+- at this point, you should have enough to generate a working HELLO WORLD
+  static binary
+
+- if you want UCLIBC_CTOR_DTOR support, you will need to create crti.S and
+  crtn.S files which define function prologues/epilogues.
+
+- for a more stable static port, you will need to create these files (and
+  update the Makefile.arch values accordingly)
+    __longjmp  bsd-_setjmp  bsd-setjmp  brk  clone  setjmp  syscall  vfork
+  usually these are written in assembler, but you may be able to cheat and
+  write them in C ... see other ports for more information
+
+====================
+=== ldso sysdeps ===
+====================
+- elf.h - presumably you've already taught binutils all about the random ELF
+  relocations your arch needs, so now you need to make sure the defines exist
+  for uClibc.  make sure the EM_### define exists and all of the R_###_###
+  reloc defines.
+
+- enable ldso/shared options in your extra/Configs/Config.ARCH file
+- you will need to create the following files in ldso/ldso/ARCH/
+  dl-startup.h  dl-syscalls.h  dl-sysdep.h  elfinterp.c  resolve.S
+
+- dl-startup.h:
+  - define the _start function which should call _dl_start which takes just one
+    parameter ... a pointer to argc (usually on the stack)
+    glibc stores this function in sysdeps/ARCH/dl-machine.h as RTLD_START
+  - define the GET_ARGV() macro which calculates the value of argv based upon
+    the parameter passed to _dl_start (usually it's simply just ARGS+1)
+  - define PERFORM_BOOTSTRAP_RELOC() macro which will handle just the relocs
+    that the ldso itself will generate
+
+- dl-syscalls.h:
+  if you wrote your bits/syscalls.h file correctly in the libc step above, you
+  can simply copy this file from another arch and be done ... otherwise you
+  will have to define the syscall[0-6] macros again, but this time setting
+  _dl_errno instead of just errno
+
+- dl-sysdep.h:
+  misc cruft goes in here ... you want to:
+  - either define or undefine ELF_USES_RELOCA
+  - define the INIT_GOT macro
+  - define MAGIC1 to the EM_### value your ELF arch uses
+  - define ELF_TARGET to a string name for your arch
+  - define the do_rem() macro
+  - define misc ALIGN macro's
+  - define elf_machine_type_class() macro
+  - define the inline functions elf_machine_dynamic, elf_machine_load_address,
+    and elf_machine_relative
+  glibc stores a bunch of these values in sysdeps/ARCH/dl-machine.h
+
+- elfinterp.c:
+  define all the relocation functions ... it's best if you just copy from
+  another arch which uses the same type of relocations (REL or RELA) and
+  start from there.
+
+- resolve.S:
+  front end of lazy relocation ... define the _dl_linux_resolve symbol which
+  is called by a PLT entry which has yet to be setup ... you will want to:
+  - set up arguments for _dl_linux_resolver()
+  - call _dl_linux_resolver()
+  - clean up after call
+  - jump to function address now stored in PLT
+  glibc stores this function in sysdeps/ARCH/dl-trampoline.S
+
+- utils/ldd.c - if you want support for ldso cache files (spoiler: you do),
+  then you'll need to teach ldd a little.  generally, the fallback code
+  should be smart and "just work", but you should be explicit.  just pop
+  it open and add an appropriate ifdef for your arch and set MATCH_MACHINE()
+  and ELFCLASSM.  there are plenty examples and you're (hopefully) smart.
+
+====================
+===  Misc Cruft  ===
+====================
+- MAINTAINERS - presumably you're going to submit this code back to mainline
+  and since you're the only one who cares about this arch (right now), you
+  should add yourself to the toplevel MAINTAINERS file.  do it.