Fix link to docs.swift.org (swiftlang#161)

Author: kubamracek

Documentation/README.md

@@ -2,5 +2,5 @@ Documentation for Embedded Swift
 ================================
 
 Documentation for Embedded Swift can be found at these locations:
-- [in rendered form](https://swiftpackageindex.com/swiftlang/swift-embedded-examples/documentation/embeddedswift)
+- [in rendered form at docs.swift.org](https://docs.swift.org/embedded/documentation/embedded/)
 - [DocC source code](/Sources/EmbeddedSwift/Documentation.docc)