I tired to edit my special characters but its not updating. I have wrote the code in the config file, but its not working

CKEDITOR.editorConfig = function( config ) {     config.specialChars = config.specialChars.concat( [['←', 'Left Arrow Bar'], [ '↑', 'Upper Arrow Bar' ],  [ '↓', 'Down Arrow Bar' ] ,['⇐','Left double Arrow' ],['⇑','Up double Arrow' ] ,['⇓','Down double Arrow' ],[ '≅', 'Congruent to' ],['√','Square Root' ],['α','Alpha'],['γ','Gamma'],['δ','Delta'],['≤','less than or equal to'],['≥','greater than or equal to']]); };