Updated README.md

Author: Ang3

README.md

@@ -107,7 +107,7 @@ Please read [phpspreadsheet documentation](https://phpspreadsheet.readthedocs.io
 - SYLK
 - CSV
 
-**/!\ When the format does not support multi-sheets (CSV for example), the only one sheet is called "Worksheet".**
+**/!\ When the format does not support multi-sheets (CSV for example), the only one sheet is called "```Worksheet```".**
 
 ```php
 <?php