Update atomic-functions.md

Author: TylerMSFT

docs/standard-library/atomic-functions.md

@@ -7,6 +7,8 @@ helpviewer_keywords: ["std::atomic_compare_exchange_strong [C++]", "std::atomic_
 ---
 # `<atomic>` functions
 
+The following functions are available in the `<atomic>` namespace:
+
 ## <a name="atomic_compare_exchange_strong"></a> `atomic_compare_exchange_strong`
 
 Performs an atomic compare and exchange operation.