Release 2020-04-15 toolchain for macOS. (#419)

swiftlang/swift@039d371

Author: dan-zheng

Installation.md

@@ -85,7 +85,7 @@ To install Swift for TensorFlow, download one of the packages below and follow t
 
 | Download |
 |----------|
-| [Xcode 11 (April 7, 2020)](https://storage.googleapis.com/swift-tensorflow/mac/swift-tensorflow-DEVELOPMENT-2020-04-07-a-osx.pkg) |
+| [Xcode 11 (April 15, 2020)](https://storage.googleapis.com/swift-tensorflow/mac/swift-tensorflow-DEVELOPMENT-2020-04-15-a-osx.pkg) |
 | [Ubuntu 18.04 (CPU Only) (Nightly)](https://storage.googleapis.com/swift-tensorflow-artifacts/nightlies/latest/swift-tensorflow-DEVELOPMENT-ubuntu18.04.tar.gz) |
 | [Ubuntu 18.04 (x10 TPU, CPU) (Nightly)](https://storage.googleapis.com/swift-tensorflow-artifacts/nightlies/latest/swift-tensorflow-DEVELOPMENT-x10-ubuntu18.04.tar.gz) |
 | [Ubuntu 18.04 (CUDA 10.1) (Nightly)](https://storage.googleapis.com/swift-tensorflow-artifacts/nightlies/latest/swift-tensorflow-DEVELOPMENT-cuda10.1-cudnn7-ubuntu18.04.tar.gz) |
@@ -103,6 +103,7 @@ To install Swift for TensorFlow, download one of the packages below and follow t
 
 | Download |
 |----------|
+| [April 7, 2020](https://storage.googleapis.com/swift-tensorflow/mac/swift-tensorflow-DEVELOPMENT-2020-04-07-a-osx.pkg) |
 | [March 25, 2020](https://storage.googleapis.com/swift-tensorflow/mac/swift-tensorflow-DEVELOPMENT-2020-03-25-a-osx.pkg) |
 | [March 20, 2020](https://storage.googleapis.com/swift-tensorflow/mac/swift-tensorflow-DEVELOPMENT-2020-03-20-a-osx.pkg) |
 | [March 17, 2020](https://storage.googleapis.com/swift-tensorflow/mac/swift-tensorflow-DEVELOPMENT-2020-03-17-a-osx.pkg) |