turn on battery pin for lora_v2 per @msws

src/configuration.h

@@ -289,6 +289,8 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define GPS_RX_PIN 36
 #define GPS_TX_PIN 13 // per @eugene
 
+#define BATTERY_PIN 35 // A battery voltage measurement pin, voltage divider connected here to measure battery voltage
+
 #define I2C_SDA 21 // I2C pins for this board
 #define I2C_SCL 22