boards/avr: rename doc.txt -> doc.md

boards/atmega256rfr2-xpro/doc.md

@@ -1,4 +1,3 @@
-/**
 @defgroup    boards_atmega256rfr2-xpro Atmega256RFR2 Xplained Pro
 @ingroup     boards
 @brief       Support for the Atmega256RFR2 Xplained Pro board
@@ -38,5 +37,3 @@ It will be used automatically with `make term`:
 ```
 make BOARD=atmega256rfr2-xpro -C examples/basic/hello-world term
 ```
-
-*/

boards/atmega8/doc.md

@@ -1,4 +1,3 @@
-/**
 @defgroup    boards_atmega8 Standalone ATmega8
 @ingroup     boards
 @brief       Support for using the ATmega8 as standalone board
@@ -95,5 +94,3 @@ Connect a TTL adapter with pins 2/RXD and 3/TXD an run
 
 Please note that the supply voltage should be compatible with the logic level of
 the TTL adapter. Usually everything between 3.3 V and 5 V should work.
-
- */

boards/atxmega-a1-xplained/doc.md

@@ -1,4 +1,3 @@
-/**
 @defgroup    boards_atxmega-a1-xplained ATxmega-A1 Xplained board
 @ingroup     boards
 @brief       Support for the ATxmega-A1 Xplained board
@@ -48,5 +47,3 @@ The CDC-ACM will enumerate a /dev/ttyACM device. The STDIO at CDC-ACM shares
 with J4 pins 2/3.
 
     make BOARD=atxmega-a1-xplained term
-
- */

boards/atxmega-a1u-xpro/doc.md

@@ -1,4 +1,3 @@
-/**
 @defgroup    boards_atxmega-a1u-xpro ATxmega-A1U Xplained Pro board
 @ingroup     boards
 @brief       Support for the ATxmega-A1U Xplained Pro board
@@ -62,5 +61,3 @@ The CDC-ACM will enumerate a /dev/ttyACM device.
 ## On-Chip Debugging (OCD)
 
     make debug
-
- */

boards/atxmega-a3bu-xplained/doc.md

@@ -1,4 +1,3 @@
-/**
 @defgroup    boards_atxmega-a3bu-xplained ATxmega-A3BU Xplained board
 @ingroup     boards
 @brief       Support for the ATxmega-A3BU Xplained board
@@ -45,5 +44,3 @@ In order to flash the ATxmega256A3BU, simple run:
 This board needs a serial converter. The default STDIO is at J1 pins 2/3.
 
     make BOARD=atxmega-a3bu-xplained term
-
- */

boards/avr-rss2/doc.md

@@ -1,4 +1,3 @@
-/**
 @defgroup    boards_avr-rss2 Atmega256RFR2 rss2
 @ingroup     boards
 @brief       Support for the Radio Sensors Atmega256RFR2 rss2 board
@@ -7,7 +6,7 @@
 Document version V1.4 2019-11-10<br>
 Board is based AtMega256RFR2 with additional HW, EUI64 chip, HW comparator, RTC XTAL, BME280
 
-- Directory `$(RIOTBASE)/boards/avr-rss2'
+- Directory `$(RIOTBASE)/boards/avr-rss2`
 
 ### Board Features
 
@@ -99,5 +98,4 @@ Contact vendor. For research legislation is more relaxed in most countries.
 
 ### Board (Rev2.4) anatomy with connectors
 - http://radio-sensors.com/pictures/s2-2.4-front-edited.jpg
-- http://radio-sensors.com/pictures/s2-2.4-back-port-edited.jpg
-*/
+- http://radio-sensors.com/pictures/s2-2.4-back-port-edited.jpg

boards/avsextrem/doc.md

@@ -1,5 +1,3 @@
-/**
 @defgroup    boards_avsextrem Avsextrem
 @ingroup     boards
 @brief       Support for the Avsextrem board
- */