add comments chapter

data/1.rust初阶/1.预备知识/1.rust简介/historyofrust.json

 {
   "type": "code_options",
-  "author": "jacky_rust",
+  "author": "jackymao_com",
   "source": "historyofrust.md",
   "notebook_enable": false,
   "exercise_id": "7e6ebda86d1e44b7974f719f08c24c7e"

data/1.rust初阶/1.预备知识/1.rust简介/rust_domains.json

 {
   "type": "code_options",
-  "author": "jacky_rust",
+  "author": "jackymao_com",
   "source": "rust_domains.md",
   "notebook_enable": false,
   "exercise_id": "b0fe573d4df14dbebab78df2415a1dbb"

data/1.rust初阶/1.预备知识/2.rust安装/rust_install.json

 {
   "type": "code_options",
-  "author": "jacky_rust",
+  "author": "jackymao_com",
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   "exercise_id": "9e8742b522af4991a36e9ac0a92b8fff"

data/1.rust初阶/1.预备知识/3.认识rust工具链/rust_toolchain.json

 {
   "type": "code_options",
-  "author": "jacky_rust",
+  "author": "jackymao_com",
   "source": "rust_toolchain.md",
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   "exercise_id": ""

data/1.rust初阶/1.预备知识/4.rustup的使用/rustup_usage.json

 {
     "type": "code_options",
-    "author": "jacky_rust",
+    "author": "jackymao_com",
     "source": "rustup_usage.md",
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     "exercise_id": ""

data/1.rust初阶/1.预备知识/5.Cargo的使用/cargo_usage.json

 {
     "type": "code_options",
-    "author": "jacky_rust",
+    "author": "jackymao_com",
     "source": "cargo_usage.md",
     "notebook_enable": false,
     "exercise_id": ""

data/1.rust初阶/2.rust基本概念/8.注释/comments.json

+{
+    "type": "code_options",
+    "author": "jackymao_com",
+    "source": "comments.md",
+    "notebook_enable": false,
+    "exercise_id": ""
+}
\ No newline at end of file

data/1.rust初阶/2.rust基本概念/8.注释/comments.md

+# 注释
+
+Rust 的注释系统是 rust 的魅力来源之一，不仅是自己写注释的时候赏心悦目，而且在阅读标准库和其它优质库时看注释都能感觉到整个 rust 社区的贴心。而且 rust 还能从注释中生成文档，甚至能运行注释中的测试代码。这让 rust 成为最贴近甚至超越经典书籍 [HTDP (How to design programs)](http://htdp.org/) 所提倡的注释的语言。
+
+Rust 常用的注释有:
+
+单行注释
+
+```rust
+// Comments always explain what exactly things are.
+```
+
+多行注释 (可以嵌套)
+```rust
+/* Although people generally use single line comments format for 
+   multiline comments, but a block comments is also needed.
+*/
+```
+
+文档注释 (三个斜杠加空格)，常放在函数或特定数据结构的上面，可以用 cargo doc 生成 HTML 文档，以网页形式查看每个函数的注释文档，非常方便于查看及跳转。常用的 IDE 还会提取这里的注释，在光标指向函数名的时候显示。
+
+```rust
+/// This add function add /// An asynchronous function from a `Request` to a `Response`.
+///
+/// The `Service` trait is a simplified interface making it easy to write
+/// network applications in a modular and reusable way, decoupled from the
+/// underlying protocol. It is one of Tower's fundamental abstractions.
+///
+/// # Functional
+```
+
+模块或库注释，两个斜杠加一个感叹号。常用在 lib.rs 的最开头部分，用于说明整个库的作用
+
+```rust
+//! Definition of the core `Service` trait to Tower
+//!
+//! The [`Service`] trait provides the necessary abstractions for defining
+//! request / response clients and servers. It is simple but powerful and is
+//! used as the foundation for the rest of Tower.
+```
+
+以下例子中的注释的使用和说明不符合注释使用规则的是：
+
+```rust
+//! A
+//! 这个库要做的事情是 blablabla...
+
+pub mod outer_module {
+
+    // B
+    //   - 我是一条注释
+    pub mod inner_module {}
+
+    pub mod nested_comments {
+
+        // C
+
+        /* 在 Rust 里面 /* 我们可以使用 /* 嵌套注释 */ */ */
+
+        // 以下三种注释都可以嵌套使用:
+
+        /*   /* */  /** */  /*! */  */
+        /*!  /* */  /** */  /*! */  */
+        /**  /* */  /** */  /*! */  */
+        pub mod dummy_item {}
+    }
+
+    pub mod degenerate_cases {
+
+        // D
+        // 空的块注释
+        /**/
+
+        pub mod dummy_item {}
+
+    }
+
+    /* The next one isn't allowed because outer doc comments
+       require an item that will receive the doc */
+
+    // E
+
+    /// 代码最尾部了，我还想写一个文档注释
+    ///
+}
+
+
+```
+
+## 答案 
+
+E
+
+## 选项
+
+###
+
+A
+
+###
+
+B
+
+###
+
+C
+
+###
+
+D

data/1.rust初阶/2.rust基本概念/8.注释/config.json

@@ -2,7 +2,9 @@
   "node_id": "rust-b76cd06f17f54e57b37cd966cd22bb85",
   "keywords": [],
   "children": [],
-  "export": [],
+  "export": [
+    "comments.json"
+  ],
   "keywords_must": [],
   "keywords_forbid": []
 }
\ No newline at end of file

data/1.rust初阶/2.rust基本概念/9.表达式/match.json

 {
   "type": "code_options",
-  "author": "jacky_rust",
+  "author": "jackymao_com",
   "source": "match.md",
   "notebook_enable": false,
   "exercise_id": "25a3a49bd39d4d0385bc4f797c3fe1e3"