enable ads1115 battery sendor monitoring

conf/layer.conf

@@ -55,6 +55,8 @@ dtoverlay=waveshare-28dpi-3b \n\
 dtoverlay=waveshare-28dpi-4b \n']['${RPI_USE_wS_28_DPI_LCD}' == '1']}"
 
 RPI_EXTRA_CONFIG += '\n\
+# enable ads1115 sensor for battery monitoring
+dtoverlay=ads1115-i2c-gpio,cha_enable,cha_cfg=4,cha_datarate=7,cha_gain=1 \n\
 #start_x=1             # essential \n\
 #gpu_mem=128           # at least, or maybe more if you wish \n\
 #disable_camera_led=1  # optional \n\