add custom font family in ckeditor

1. Add font in build-config.js

plugins : {
	.........
    .......
	'font' : 1,
    ......
    .......
}

2. add font face inside the css file or head of html tag
 
 @font-face {
   font-family: 'PRKSI';
   src: url('/fonts/PRKSI.ttf') format('truetype');
 }

3. Then add font_name inside config.js

config.font_names = config.font_names + ';PRKSI';

reference :
https://ckeditor.com/docs/ckeditor4/latest/api/CKEDITOR_config.html#cfg-font_defaultLabel