Add Golang/Go-Unstable versions "1.15-beta1" (#2279)

* Create 1.15-beta1.yaml

* Update 1.15-beta1.yaml

manifests/Golang/Go-Unstable/1.15-beta1.yaml

@@ -0,0 +1,16 @@
+Id: Golang.Go-Unstable
+Version: 1.15-beta1
+Name: Go
+Publisher: Golang
+License: Copyright (c) 2009 The Go Authors
+LicenseUrl: https://github.com/golang/go/blob/go1.15beta1/LICENSE
+AppMoniker: go-unstable
+Tags: go, golang, go1.15, golang1.15, go-unstable, golang-unstable
+Description: Go is an open source programming language that makes it easy to build simple, reliable, and efficient software.
+Homepage: https://golang.org
+
+Installers:
+  - InstallerType: msi
+    Arch: x64
+    Url: https://dl.google.com/go/go1.15beta1.windows-amd64.msi
+    Sha256: F24171255FA1EBF5383A4D4E6C22FC1D5BF9A3853DB8B1E74E6A0CE79E0F1C2A