Update README.md

fixed a typo;

README.md

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 # Sound Wizard
-A simple media player was written in C#. It uses [WPF](https://github.com/Microsoft/WPF-Samples) and [Mahapps Metro Toolkit](https://github.com/MahApps/MahApps.Metro) for the interface.
+A simple media player written in C#. It uses [WPF](https://github.com/Microsoft/WPF-Samples) and [Mahapps Metro Toolkit](https://github.com/MahApps/MahApps.Metro) for the interface.
 
 This is our [C# Advanced OOP teamwork](https://softuni.bg/trainings/1637/c-sharp-oop-advanced-july-2017#lecture-6062) project and its main purpose is to help us learn around a real-world application.
 
-Our goal is to work in a team, to try to follow MVVM design architecture and OOP best practices.
+Our goal is to work in a team, to try to follow MVVM design architecture and OOP best practices.