Add missing documentation for dev.acpi_ibm.0.mic_led added in r335304

PR:		229074
X-MFC-With:	335304
Submitted by:	Ali Abdallah <aliovx@gmail.com>

share/man/man4/acpi_ibm.4

@@ -273,6 +273,9 @@ Current brightness level of the display.
 Speaker volume.
 .It Va dev.acpi_ibm.0.mute
 Indicates, whether the speakers are muted or not.
+.It Va dev.acpi_ibm.0.mic_mute
+Indicates, whether the microphone led (present on some model) is on or not. 
+Note that this does not mean that the microphone input is muted.
 .It Va dev.acpi_ibm.0.thinklight
 Indicates, whether the ThinkLight keyboard light is activated or not.
 .It Va dev.acpi_ibm.0.bluetooth
@@ -437,6 +440,17 @@ case ${NOTIFY} in
                         MESSAGE="volume unmuted"
                 fi
                 ;;
+	0x1b)
+		LEVEL=`sysctl -n dev.acpi_ibm.0.mic_led`
+		if [ $LEVEL -eq 0 ]; then
+			sysctl dev.acpi_ibm.0.mic_led=1
+			mixer rec 0
+		fi 
+		if [ $LEVEL -eq 1 ]; then 
+			sysctl dev.acpi_ibm.0.mic_led=0
+			mixer rec 30
+		fi
+		;;
         *)
                 ;;
 esac