Add note about .sh file

Author: soundanalogous

release.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-# use this script to package Firmata for distribution
+# [Optional] use this script to package Firmata for distribution
 
 # package for Arduino 1.0.x
 mkdir -p temp/Firmata
@@ -15,7 +15,7 @@ cd temp
 find . -name "*.DS_Store" -type f -delete
 zip -r Firmata.zip ./Firmata/
 cd ..
-mv ./temp/Firmata.zip Arduino-1.0.x-Firmata-2.5.8.zip
+mv ./temp/Firmata.zip Arduino-1.0.x-Firmata-2.5.9.zip
 
 #package for Arduino 1.6.x and 1.8.x
 cp library.properties temp/Firmata
@@ -29,5 +29,5 @@ cd ..
 find . -name "*.DS_Store" -type f -delete
 zip -r Firmata.zip ./Firmata/
 cd ..
-mv ./temp/Firmata.zip Firmata-2.5.8.zip
+mv ./temp/Firmata.zip Firmata-2.5.9.zip
 rm -r ./temp