doc: add wiki documentation to Doxygen files

boards/acd52832/doc.txt

boards/airfy-beacon/doc.txt

boards/arduino-due/doc.txt

boards/arduino-duemilanove/doc.txt

boards/arduino-mega2560/doc.txt

boards/arduino-mkr1000/doc.txt

boards/arduino-mkrfox1200/doc.txt

boards/arduino-mkrzero/doc.txt

boards/arduino-uno/doc.txt

boards/arduino-zero/doc.txt

boards/avsextrem/doc.txt

boards/b-l072z-lrwan1/doc.txt

boards/b-l475e-iot01a/doc.txt

boards/bluepill/doc.txt

boards/calliope-mini/doc.txt

boards/cc2538dk/doc.txt

boards/cc2650-launchpad/doc.txt

boards/cc2650stk/doc.txt

boards/chronos/doc.txt

boards/common/doc.txt