Add Debian manifest (#844)

manifests/Debian/Debian/9.0.yaml

@@ -0,0 +1,15 @@
+Id: Debian.Debian
+Version: 9.0
+Name: Debian
+Publisher: Debian
+License: Copyright The Debian Project
+LicenseUrl: https://www.debian.org/legal/licenses/
+AppMoniker: debian
+Tags: linux, debian, distro, wsl
+Homepage: https://debian.org
+Installers:
+  - Arch: x64
+    Url: https://aka.ms/wsl-debian-gnulinux
+    Sha256: 02CC1CE48E2FC21331B6FAA2AF44F22FBB9E9C219EAF74202970164BE6E3D3D8
+    InstallerType: appx
+