Add `$schema` to `cgmanifest.json` (#1082)

Co-authored-by: Jamie Magee <jamie.magee@microsoft.com>

src/Qir/Common/Externals/cgmanifest.json

@@ -1,30 +1,33 @@
 {
-    "Registrations":[
-        {
-            "Component": {
-                "Type": "other",
-                "Other": {
-                    "Name": "llvm-ar.exe",
-                    "Version": "10.0.0",
-                    "DownloadUrl": "https://github.com/llvm/llvm-project/releases/download/llvmorg-10.0.0/LLVM-10.0.0-win64.exe"
-                }
-            }
-        },
-        {
-            "Component": {
-                "Type": "git",
-                "Git": { 
-                    "RepositoryUrl": "https://github.com/catchorg/Catch2", 
-                    "CommitHash": "87074da73ecb1c2e7c35fd14f50ca21c4c002adc" }
-            }
-        },
-        {
-            "Component": {
-                "Type": "git",
-                "Git": { 
-                    "RepositoryUrl": "https://github.com/CLIUtils/CLI11", 
-                    "CommitHash": "5cb3efabce007c3a0230e4cc2e27da491c646b6c" }
-            }
+  "$schema": "https://json.schemastore.org/component-detection-manifest.json",
+  "Registrations": [
+    {
+      "Component": {
+        "Type": "other",
+        "Other": {
+          "Name": "llvm-ar.exe",
+          "Version": "10.0.0",
+          "DownloadUrl": "https://github.com/llvm/llvm-project/releases/download/llvmorg-10.0.0/LLVM-10.0.0-win64.exe"
         }
-    ]
-}
+      }
+    },
+    {
+      "Component": {
+        "Type": "git",
+        "Git": {
+          "RepositoryUrl": "https://github.com/catchorg/Catch2",
+          "CommitHash": "87074da73ecb1c2e7c35fd14f50ca21c4c002adc"
+        }
+      }
+    },
+    {
+      "Component": {
+        "Type": "git",
+        "Git": {
+          "RepositoryUrl": "https://github.com/CLIUtils/CLI11",
+          "CommitHash": "5cb3efabce007c3a0230e4cc2e27da491c646b6c"
+        }
+      }
+    }
+  ]
+}