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@sumn2u has made changes on the original english version of the book (PR #167)

Visual Diff of Changes:

diff --git a/en/SUMMARY.md b/en/SUMMARY.md
index 3cfa07a..a00ee70 100644
--- a/en/SUMMARY.md
+++ b/en/SUMMARY.md
@@ -72,7 +72,7 @@
   - [History](browser-object-model-bom/history.md)
   - [Location](browser-object-model-bom/location.md)
 - [Events](events.md)
-- [Promise, async/await](promise-async-await/promise.md)
+- [Promise, async/await](promise-async-await/README.md)
   - [Promise](promise-async-await/promise.md)
   - [Async/Await](promise-async-await/async-await.md)
 - [Miscellaneous](miscellaneous/README.md)
diff --git a/en/promise-async-await/README.md b/en/promise-async-await/README.md
index 483ce78..766f840 100644
--- a/en/promise-async-await/README.md
+++ b/en/promise-async-await/README.md
@@ -8,4 +8,7 @@ description: Promises are now used by most modern APIs. It is therefore importan
 # Chapter 18
 # Promise, async/await

-Promises are now used by most modern APIs. It is therefore important to understand how they work and to know how to use them to optimize your code. In this chapter, we'll define in detail what promises are and how to use them in asynchronous operations.
\ No newline at end of file
+Promises are now used by most modern APIs. It is therefore important to understand how they work and to know how to use them to optimize the code. In this chapter, we'll define in detail what promises are and how to use them in asynchronous operations.
+
+* [Promise](./promise.md)
+* [Async/Await](./async-await.md)
\ No newline at end of file