[README] Coarse sweep to use markup in READMEs.

This should improve online readability of the readme files.

examples/stm32/f1/stm32-maple/miniblink/README.md

@@ -1,9 +1,7 @@
-------------------------------------------------------------------------------
-README
-------------------------------------------------------------------------------
+# README
 
 This is the smallest-possible example program using libopencm3.
 
-It's intended for the ST STM32-based Leaf Labs Maple board (see
-http://leaflabs.com for details). It should blink the LED on the board.
-
+It's intended for the ST STM32-based
+[Leaf Labs Maple board](http://leaflabs.com).
+It should blink the LED on the board.

examples/stm32/f1/stm32-maple/usart/README.md

@@ -1,13 +1,10 @@
-------------------------------------------------------------------------------
-README
-------------------------------------------------------------------------------
+# README
 
 This example program sends some characters on USART3 on the ST STM32-based
-Olimex STM32-H103 eval board (see http://olimex.com/dev/stm32-h103.html
-for details).
+[Olimex STM32-H103 eval board](http://olimex.com/dev/stm32-h103.html).
 
 The terminal settings for the receiving device/PC are 38400 8n1.
 
-The sending is done in a blocking way in the code, see the usart_irq example
+The sending is done in a blocking way in the code, see the usart\_irq example
 for a more elaborate USART example.
 

examples/stm32/f1/stm32-maple/usb_cdcacm/README.md

@@ -1,7 +1,5 @@
-------------------------------------------------------------------------------
-README
-------------------------------------------------------------------------------
+# README
 
-This example implements a USB CDC-ACM device (aka Virtual Serial Port)
-to demonstrate the use of the USB device stack.
+This example implements a USB CDC-ACM device (aka Virtual Serial Port) to
+demonstrate the use of the USB device stack.