Adding link to Douglas Gregor's generics manifesto

Author: austinzheng

README.md

@@ -38,7 +38,7 @@ concretely, this release is focused on several key areas:
  * *How do we maintain high performance?*: Resilient implementations often incur more execution overhead than non-resilient (or *fragile*) implementations, because resilient implementations need to leave some details unspecified until load time, such as the specific sizes of a class or offsets of a stored property.
 * **Portability**: Make Swift available on other platforms and ensure that one can write portable Swift code that works properly on all of those platforms.
 * **Type system cleanup and documentation**: Revisit and document the various subtyping and conversion rules in the type system, as well as their implementation in the compiler's type checker. The intent is to converge on a smaller, simpler type system that is more rigorously defined and more faithfully represented by the type checker.
-* **Complete generics**: Generics are used pervasively in a number of Swift libraries, especially the standard library. However, there are a number of generics features the standard library requires to fully realize its vision, including recursive protocol constraints, the ability to make a constrained extension conform to a new protocol (i.e., an array of `Equatable` elements is `Equatable`), and so on. Swift 3.0 should provide those generics features needed by the standard library, because they affect the standard library's ABI.
+* **Complete generics**: Generics are used pervasively in a number of Swift libraries, especially the standard library. However, there are a number of generics features the standard library requires to fully realize its vision, including recursive protocol constraints, the ability to make a constrained extension conform to a new protocol (i.e., an array of `Equatable` elements is `Equatable`), and so on. Swift 3.0 should provide those generics features needed by the standard library, because they affect the standard library's ABI. For more information on generics as envisioned for Swift, please see [Douglas Gregor's *Completing Generics* manifesto](https://github.com/apple/swift/blob/master/docs/GenericsManifesto.md).
 * **Focus and refine the language**: Despite being a relatively young language, Swift's rapid development has meant that it has accumulated some language features and library APIs that don't fit well with the language as a whole. Swift 3 will remove or improve those features to provide better overall consistency for Swift.
 * **API design guidelines**: The way in which Swift is used in popular
  libraries has almost as much of an effect on the character of Swift