Upodate changelog for release 3.0.0

Author: NickNaso

CHANGELOG.md

@@ -5,6 +5,8 @@
 * Complete the port to N-API using node-addon-api
 * Undefinedfilename error on Windows if file path contains spaces - Fix issue [#33](https://github.com/NickNaso/ghostscript4js/issues/33)
 * Added code of conduct
+* Small updates on documentation - executeSync and execute function allow to pass array of strings as arguments.
+* Verifired and updated the compatibility against the ghostscript version 9.23
 
 ## 2.0.11-n-api / 2018-03-22