Add link to the Language Server Protocol website

This should improve readability of the `README.md` file

Author: MaxDesiatov

README.md

@@ -6,7 +6,7 @@ We’ve designed the system to make it easy to share packages on services like G
 
 Swift Package Manager includes a build system that can build for macOS and Linux. Xcode 11 integrates with libSwiftPM to provide support for iOS, watchOS, and tvOS platforms.
 
-The [SourceKit-LSP](https://github.com/apple/sourcekit-lsp) project leverages libSwiftPM and provides Language Server Protocol implementation for editors that support LSP.
+The [SourceKit-LSP](https://github.com/apple/sourcekit-lsp) project leverages libSwiftPM and provides [Language Server Protocol](https://langserver.org/) implementation for editors that support LSP.
 
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