Fixup relative readme link (#336)

Issue: #334

Author: plemarquand

README.md

@@ -61,7 +61,7 @@ This command checks to see if there are new versions of swiftly itself and upgra
 
 Welcome to the Swift community!
 
-Contributions to Swiftly are welcomed and encouraged! Please see the [Contributing to Swift guide](swift.org/contributing) and check out the [structure of the community](https://www.swift.org/community/#community-structure).
+Contributions to Swiftly are welcomed and encouraged! Please see the [Contributing to Swift guide](https://www.swift.org/contributing) and check out the [structure of the community](https://www.swift.org/community/#community-structure).
 
 To be a truly great community, Swift needs to welcome developers from all walks of life, with different backgrounds, and with a wide range of experience. A diverse and friendly community will have more great ideas, more unique perspectives, and produce more great code. We will work diligently to make the Swift community welcoming to everyone.