Merge pull request #1216 from shaggygi/patch-1

Update README.md

Author: tocsoft

README.md

@@ -19,7 +19,7 @@ SixLabors.ImageSharp
 
 ImageSharp is a new, fully featured, fully managed, cross-platform, 2D graphics library. Designed to simplify image processing, ImageSharp brings you an incredibly powerful yet beautifully simple API.
 
-ImageSharp is designed from the ground up to be flexible and extensible. The library provides API endpoints for common image processing operations and the building blocks to allow for the development of addtional operations.
+ImageSharp is designed from the ground up to be flexible and extensible. The library provides API endpoints for common image processing operations and the building blocks to allow for the development of additional operations.
 
 Built against [.NET Standard 1.3](https://docs.microsoft.com/en-us/dotnet/standard/net-standard), ImageSharp can be used in device, cloud, and embedded/IoT scenarios.