see #2: update exercises and maintains of content

book/en-us/toc.md

@@ -76,13 +76,14 @@
         + `std::regex`
         + `std::regex_match`
         + `std::match_results`
-- [**Chapter 07 Sandard Library: Threads and Concurrency**](./07-thread.md)
+- [**Chapter 07 Parallelism and Concurrency**](./07-thread.md)
     + 7.1 `std::thread`
     + 7.2 `std::mutex` and `std::unique_lock`
     + 7.3 `std::future` and `std::packaged_task`
     + 7.4 `std::condition_variable`
     + 7.5 `std::atomic` and memory order
     + 7.6 Transactional memory
+    + 7.7 Coroutine
 - [**Chapter 08 Sandard Library: File System**](./08-filesystem.md)
     + 8.1 Documents and links
     + 8.2 `std::filesystem`