doc: added comments to code

cherrypick_annotations/lib/src/module.dart

@@ -1,5 +1,24 @@
-/// Отмечает класс как injectable для автоматической регистрации.
+/// An annotation used to mark a Dart class or library as a module.
+///
+/// This annotation can be used for tooling, code generation,
+/// or to provide additional metadata about the module.
+///
+/// Example:
+/// ```dart
+/// @module()
+/// abstract class AppModule extends Module {
+/// }
+/// ```
+/// Сгенерирует код:
+/// ```dart
+/// final class $AppModule extends AppModule {
+///   @override
+///   void builder(Scope currentScope) {
+///
+///   }
+/// }
 // ignore: camel_case_types
-class module {
+final class module {
+  /// Creates a [module] annotation.
   const module();
 }