Blockly:MATH CHANGE HELPURL/ru

https://ru.wikipedia.org/wiki/%D0%98%D0%B4%D0%B8%D0%BE%D0%BC%D0%B0_%28%D0%BF%D1%80%D0%BE%D0%B3%D1%80%D0%B0%D0%BC%D0%BC%D0%B8%D1%80%D0%BE%D0%B2%D0%B0%D0%BD%D0%B8%D0%B5%29#.D0.98.D0.BD.D0.BA.D1.80.D0.B5.D0.BC.D0.B5.D0.BD.D1.82