WIP: Update README

README.md

 micropython fork with card10 support
 ------------------------------------
 
-Original README in [`README-OLD.md`](./README-OLD.md)
+Original README in [`README-OLD.md`](./README-OLD.md).
+`card10` specific code is in [`ports/card10`](./ports/card10).
+
+## Building
+
+Build the card10 port using
+```bash
+cd ports/card10
+make SDK_LOCATION=/path/to/firmware/sdk
+```
+If everything goes well, you'll end up with a file `ports/card10/build/firmware.elf`.

ports/card10/README.md

-# The minimal port
-
-This port is intended to be a minimal MicroPython port that actually runs.
-It can run under Linux (or similar) and on any STM32F4xx MCU (eg the pyboard).
-
-## Building and running Linux version
-
-By default the port will be built for the host machine:
-
-    $ make
-
-To run the executable and get a basic working REPL do:
-
-    $ make run
-
-## Building for an STM32 MCU
-
-The Makefile has the ability to build for a Cortex-M CPU, and by default
-includes some start-up code for an STM32F4xx MCU and also enables a UART
-for communication.  To build:
-
-    $ make CROSS=1
-
-If you previously built the Linux version, you will need to first run
-`make clean` to get rid of incompatible object files.
-
-Building will produce the build/firmware.dfu file which can be programmed
-to an MCU using:
-
-    $ make CROSS=1 deploy
-
-This version of the build will work out-of-the-box on a pyboard (and
-anything similar), and will give you a MicroPython REPL on UART1 at 9600
-baud.  Pin PA13 will also be driven high, and this turns on the red LED on
-the pyboard.
-
-## Building without the built-in MicroPython compiler
-
-This minimal port can be built with the built-in MicroPython compiler
-disabled.  This will reduce the firmware by about 20k on a Thumb2 machine,
-and by about 40k on 32-bit x86.  Without the compiler the REPL will be
-disabled, but pre-compiled scripts can still be executed.
-
-To test out this feature, change the `MICROPY_ENABLE_COMPILER` config
-option to "0" in the mpconfigport.h file in this directory.  Then
-recompile and run the firmware and it will execute the frozentest.py
-file.