README: correct link to Carthage instructions.

Now also works in mobile.

Author: kareman

README.md

@@ -172,7 +172,7 @@ and run `swift build`.
 
 Add `github "kareman/FileSmith"` to your Cartfile, then run `carthage update` and add the resulting framework to the "Embedded Binaries" section of the application. See [Carthage's README][carthage-installation] for further instructions.
 
-[carthage-installation]: https://github.com/Carthage/Carthage#adding-frameworks-to-an-application
+[carthage-installation]: https://github.com/Carthage/Carthage/blob/master/README.md#adding-frameworks-to-an-application
 
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