Brightness (Linux): detect brightness of external monitors with DDC/CI

src/data/config_user.txt

@@ -458,3 +458,5 @@
 #--lib-opencl /usr/lib/libOpenCL.so
 #--lib-freetype /data/data/com.termux/files/usr/lib
 #--lib-pulse /usr/lib/libpulse.so
+#--lib-ddcutil /usr/lib/libddcutil.so
+#--lib-nm /usr/lib/libnm.so

src/data/help.txt

@@ -99,6 +99,7 @@ Library options: Set the path of a library to load
     --lib-opencl <path>
     --lib-pulse <path>
     --lib-freetype <path>
+    --lib-ddcutil <path>
 
 Module specific options:
     --title-fqdn <?value>:                   Set if the title should use fully qualified domain name. Default is false