Updates repo javadoc

Author: JoseAlcerreca

app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/source/DefaultTasksRepository.kt

@@ -26,7 +26,7 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 
 /**
- * TODO
+ * Default implementation of [TasksRepository]. Single entry point for managing tasks' data.
  */
 class DefaultTasksRepository(
     private val tasksRemoteDataSource: TasksDataSource,