Fix spelling errors for 'visualizer'

Closes dotnet#469

README.md

@@ -7,7 +7,7 @@
 
 # What is the Roslyn-SDK?
 
-Roslyn is the compiler platform for .NET. It consists of the compiler itself and a powerful set of APIs to interact with the compiler. The Roslyn platform is hosted at [github.com/dotnet/roslyn](https://github.com/dotnet/roslyn). The compiler is part of every .NET installation. The APIs to interact with the compiler are available via NuGet (see the [Roslyn repository](https://github.com/dotnet/roslyn) for details). The Roslyn SDK includes additional components to get you started with advanced topics such as distributing a Roslyn analyzer as Visual Studio extension or to inspect code with the Syntax Vizualizer. The documentation for the Roslyn platform can be found at [docs.microsoft.com/dotnet/csharp/roslyn-sdk](https://docs.microsoft.com/dotnet/csharp/roslyn-sdk). This repository contains code for both the Roslyn-SDK templates and Syntax Vizualizer.
+Roslyn is the compiler platform for .NET. It consists of the compiler itself and a powerful set of APIs to interact with the compiler. The Roslyn platform is hosted at [github.com/dotnet/roslyn](https://github.com/dotnet/roslyn). The compiler is part of every .NET installation. The APIs to interact with the compiler are available via NuGet (see the [Roslyn repository](https://github.com/dotnet/roslyn) for details). The Roslyn SDK includes additional components to get you started with advanced topics such as distributing a Roslyn analyzer as Visual Studio extension or to inspect code with the Syntax Visualizer. The documentation for the Roslyn platform can be found at [docs.microsoft.com/dotnet/csharp/roslyn-sdk](https://docs.microsoft.com/dotnet/csharp/roslyn-sdk). This repository contains code for both the Roslyn-SDK templates and Syntax Visualizer.
 
 # Installation instructions