Add a porting doc and make a pass over the others.

Fixes #5

hw/bsp/readme.md

@@ -7,14 +7,23 @@ This code base already had supported for a handful of boards. However due to my
 ### NXP MCU ###
 
 - [LPCXpresso 11u14](http://www.embeddedartists.com/products/lpcxpresso/lpc11U14_xpr.php) with base board (for some peripherals to work)
-- [<b>LPCXpresso 1347</b>](http://www.embeddedartists.com/products/lpcxpresso/lpc1347_xpr.php) with base board (for some peripherals to work)
-- [<b>LPCXpresso 1769</b>](http://www.embeddedartists.com/products/lpcxpresso/lpc1347_xpr.php) with base board (for some peripherals to work)
-- [<b>Embedded Artists LPC4357 OEM & Base board</b>](http://www.embeddedartists.com/products/kits/lpc4357_kit.php)
-- [<b>NGX LPC4330 Explorer</b>](http://shop.ngxtechnologies.com/product_info.php?products_id=104)
+- [**LPCXpresso 1347**](http://www.embeddedartists.com/products/lpcxpresso/lpc1347_xpr.php) with base board (for some peripherals to work)
+- [**LPCXpresso 1769**](http://www.embeddedartists.com/products/lpcxpresso/lpc1347_xpr.php) with base board (for some peripherals to work)
+- [**Embedded Artists LPC4357 OEM & Base board**](http://www.embeddedartists.com/products/kits/lpc4357_kit.php)
+- [**NGX LPC4330 Explorer**](http://shop.ngxtechnologies.com/product_info.php?products_id=104)
 - [Keil MCB4357 Evaluation Board](http://www.keil.com/mcb4300)
 
+### MicroChip SAMD ###
+
+- [**Adafruit Metro M0 Express**](https://www.adafruit.com/product/3505)
+- [**Adafruit Metro M4 Express**](https://www.adafruit.com/product/3382)
+
+### Nordic nRF52840 ###
+
+- [**nRF52840-DK (aka pca10056)**](https://www.nordicsemi.com/eng/Products/nRF52840-DK)
+
 ## Add your own board ##
 
 If you don't possess any of supported board above. Don't worry you can easily implemented your own one by following this guide as long as the mcu is supported.
 
-**Guide to implement a new board is coming soon** ...
+**Guide to implement a new board is coming soon** ...