small typo fix

README.md

 
 * [PHPWord](https://github.com/PHPOffice/PHPWord) - A library for working with Microsoft Word documents.
 * [PHPExcel](https://github.com/PHPOffice/PHPExcel) - A library for working with Microsoft Excel documents.
-* [PHPPowerPoint](https://github.com/PHPOffice/PHPPowerPoint) - A library for working with Microsoft Word documents.
+* [PHPPowerPoint](https://github.com/PHPOffice/PHPPowerPoint) - A library for working with Microsoft PowerPoint Presentations.
 * [ExcelAnt](https://github.com/Wisembly/ExcelAnt) - A library for manipulating Microsoft Excel documents.
 
 ## Database