Update README.md

Author: swhitty

README.md

@@ -210,3 +210,10 @@ extension UIImage {
 ```
 
 Source code can be generated using [www.whileloop.com/swiftdraw](https://www.whileloop.com/swiftdraw).
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+# Credits
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+SwiftDraw is primarily the work of [Simon Whitty](https://github.com/swhitty).
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+([Full list of contributors](https://github.com/swhitty/SwiftDraw/graphs/contributors))