add C/C++面向WebAssembly编程 (#3049)

free-programming-books-zh.md

@@ -65,6 +65,7 @@
   * [Swift](#swift)
   * [Vim](#vim)
   * [Visual Prolog](#visual-prolog)
+  * [WebAssembly](#webassembly)
 
 
 ## 语言无关
@@ -693,3 +694,8 @@
 
 * [Visual Prolog 7初学指南](http://wiki.visual-prolog.com/index.php?title=A_Beginners_Guide_to_Visual_Prolog_in_Chinese)
 * [Visual Prolog 7边练边学](http://wiki.visual-prolog.com/index.php?title=Visual_Prolog_for_Tyros_in_Chinese)
+
+
+### WebAssembly
+
+* [C/C++面向WebAssembly编程](https://github.com/3dgen/cppwasm-book)