Update Changelog.md

Author: GregorBiswanger

Changelog.md

@@ -7,7 +7,7 @@ ElectronNET.CLI:
 ElectronNET.API:
 
 * Fixed bug: Menu Item visibility [\#257](https://github.com/ElectronNET/Electron.NET/issues/257)
-* Fixed bug: electron.manifest.json - singleInstance not working [/#258](https://github.com/ElectronNET/Electron.NET/issues/258)
+* Fixed bug: electron.manifest.json - singleInstance not working [\#258](https://github.com/ElectronNET/Electron.NET/issues/258)
 
 ElectronNET.WebApp: