Add Go AST Book (#3617)

* Update free-programming-books-zh.md

* Update free-programming-books-zh.md

free-programming-books-zh.md

@@ -398,6 +398,7 @@
 * [Go 指南](https://tour.go-zh.org/list) (《A Tour of Go》中文版)
 * [Go 简易教程](https://github.com/songleo/the-little-go-book_ZH_CN) (《[The Little Go Book](https://github.com/karlseguin/the-little-go-book)》中文版)
 * [Go 编程基础](https://github.com/Unknwon/go-fundamental-programming)
+* [Go 语法树入门](https://github.com/chai2010/go-ast-book)
 * [Go 语言实战笔记](https://github.com/rujews/go-in-action-notes)
 * [Go 语言标准库](https://github.com/polaris1119/The-Golang-Standard-Library-by-Example)
 * [Go 语言高级编程（Advanced Go Programming）](https://github.com/chai2010/advanced-go-programming-book)