Update RF24.h - Add comments for github.io

RF24.h

@@ -1845,6 +1845,62 @@ private:
  * <br><br><br>
  *
  * 
+ * @page ATXMEGA ATXMEGA
+ * 
+ * The RF24 driver can be build as a static library with Atmel Studio 7 in order to be included as any other library in another program for the XMEGA family.
+ *
+ * Currently only the </b>ATXMEGA256D3</b> is implemented.
+ * 
+ * @section Preparation 
+ * 
+ * Create an empty GCC Static Library project in AS7.<br>
+ * As not all files are required, copy the following directory structure in the project:
+ * 
+ * @code
+ * utility\
+ *   ATXMega256D3\
+ *     compatibility.c
+ *     compatibility.h
+ *     gpio.cpp
+ *     gpio.h
+ *     gpio_helper.c
+ *     gpio_helper.h
+ *     includes.h
+ *     RF24_arch_config.h
+ *     spi.cpp
+ *     spi.h
+ * nRF24L01.h
+ * printf.h
+ * RF24.cpp
+ * RF24.h
+ * RF24_config.h
+ * @endcode
+ * 
+ * @section Usage
+ * 
+ * Add the library to your project!</br>
+ * In the file where the **main()** is put the following in order to update the millisecond functionality:
+ * 
+ * @code
+ * ISR(TCE0_OVF_vect)
+ * {
+ * 	update_milisec();
+ * }
+ * @endcode
+ * 
+ * Declare the rf24 radio with **RF24 radio(XMEGA_PORTC_PIN3, XMEGA_SPI_PORT_C);**
+ * 
+ * First parameter is the CE pin which can be any available pin on the uC.
+ * 
+ * Second parameter is the CS which can be on port C (**XMEGA_SPI_PORT_C**) or on port D (**XMEGA_SPI_PORT_D**). 
+ * 
+ * Call the **__start_timer()** to start the millisecond timer.
+ * 
+ * @note Note about the millisecond functionality:<br>
+ * 
+ * 	The millisecond functionality is based on the TCE0 so don't use these pins as IO.<br>
+ * 	The operating frequency of the uC is 32MHz. If you have other frequency change the TCE0 registers appropriatly in function **__start_timer()** in **compatibility.c** file for your frequency. 
+ *
  * @page Portability RF24 Portability
  *
  * The RF24 radio driver mainly utilizes the <a href="http://arduino.cc/en/reference/homePage">Arduino API</a> for GPIO, SPI, and timing functions, which are easily replicated