Add a script to help find undocumented settings

_config.yml

@@ -2,6 +2,9 @@ name: Dart Code
 desc: Dart & Flutter support for Visual Studio Code
 permalink: /:name/
 excerpt_separator: ""
+exclude:
+  - pubspec.yaml
+  - tool/
 collections:
   docs:
     output: true

pubspec.yaml

@@ -0,0 +1,4 @@
+name: dart_code_website
+
+dependencies:
+  path:

tool/validate.dart

@@ -0,0 +1,25 @@
+import 'dart:convert';
+import 'dart:io';
+import 'package:path/path.dart';
+
+main() {
+  Directory.current = dirname(Platform.script.toFilePath());
+
+  final packageFile = File('../../Dart-Code/package.json');
+  final packageManifest = jsonDecode(packageFile.readAsStringSync());
+  final Map<String, dynamic> configOptions =
+      packageManifest['contributes']['configuration']['properties'];
+
+  validateSettingsDoc(configOptions);
+}
+
+void validateSettingsDoc(Map<String, dynamic> configOptions) {
+  final settingsFile = File('../_docs/settings.md');
+  final settingsContent = settingsFile.readAsStringSync();
+
+  configOptions.forEach((name, options) {
+    if (!settingsContent.contains('## $name')) {
+      print('Setting $name does not appear in docs!');
+    }
+  });
+}