common.h: Add Doxygen main page text.

include/libopencm3/cm3/common.h

@@ -38,4 +38,20 @@ typedef uint64_t u64;
 #define MMIO32(addr)		(*(volatile u32 *)(addr))
 #define MMIO64(addr)		(*(volatile u64 *)(addr))
 
+/* Main page for the doxygen-generated documentation: */
+
+/**
+ * @mainpage libopencm3 Developer Documentation
+ *
+ * The libopencm3 project (previously known as libopenstm32) aims to create
+ * a free/libre/open-source (GPL v3, or later) firmware library for various
+ * ARM Cortex-M3 microcontrollers, including ST STM32, Toshiba TX03,
+ * Atmel SAM3U, NXP LPC1000 and others.
+ *
+ * @par ""
+ *
+ * See the <a href="http://www.libopencm3.org">libopencm3 wiki</a> for
+ * more information.
+ */
+
 #endif