fix(#1904): update doc tests to use playground as the crate name

This updates the Documentation Testing (21.2) chapter to assume a crate
name of `playground` instead of `doccomments`. This allows for the code
contained within to be copy-pasted directly into play.rust-lang.org to
run; anyone who would want to reproduce this locally would want to
create a `playground` library.

Fixes #1904.

Author: mautamu

po/es.po

@@ -14221,11 +14221,11 @@ msgid ""
 "///\n"
 "/// The next lines present detailed documentation. Code blocks start with\n"
 "/// triple backquotes and have implicit `fn main()` inside\n"
-"/// and `extern crate <cratename>`. Assume we're testing `doccomments` "
-"crate:\n"
+"/// and `extern crate <cratename>`. Assume we're testing a `playground` library\n"
+"/// crate or using the Playground's Test action:\n"
 "///\n"
 "/// ```\n"
-"/// let result = doccomments::add(2, 3);\n"
+"/// let result = playground::add(2, 3);\n"
 "/// assert_eq!(result, 5);\n"
 "/// ```\n"
 msgstr ""
@@ -14240,7 +14240,7 @@ msgid ""
 "/// # Examples\n"
 "///\n"
 "/// ```\n"
-"/// let result = doccomments::div(10, 2);\n"
+"/// let result = playground::div(10, 2);\n"
 "/// assert_eq!(result, 5);\n"
 "/// ```\n"
 "///\n"
@@ -14250,7 +14250,7 @@ msgid ""
 "///\n"
 "/// ```rust,should_panic\n"
 "/// // panics on division by zero\n"
-"/// doccomments::div(10, 0);\n"
+"/// playground::div(10, 0);\n"
 "/// ```\n"
 msgstr ""
 
@@ -14285,7 +14285,7 @@ msgid ""
 "/// # // hidden lines start with `#` symbol, but they're still compilable!\n"
 "/// # fn try_main() -> Result<(), String> { // line that wraps the body "
 "shown in doc\n"
-"/// let res = doccomments::try_div(10, 2)?;\n"
+"/// let res = playground::try_div(10, 2)?;\n"
 "/// # Ok(()) // returning from try_main\n"
 "/// # }\n"
 "/// # fn main() { // starting main that'll unwrap()\n"

po/ja.po

@@ -16185,11 +16185,11 @@ msgid ""
 "///\n"
 "/// The next lines present detailed documentation. Code blocks start with\n"
 "/// triple backquotes and have implicit `fn main()` inside\n"
-"/// and `extern crate <cratename>`. Assume we're testing `doccomments` "
-"crate:\n"
+"/// and `extern crate <cratename>`. Assume we're testing a `playground` library\n"
+"/// crate or using the Playground's Test action:\n"
 "///\n"
 "/// ```\n"
-"/// let result = doccomments::add(2, 3);\n"
+"/// let result = playground::add(2, 3);\n"
 "/// assert_eq!(result, 5);\n"
 "/// ```\n"
 msgstr ""
@@ -16198,10 +16198,10 @@ msgstr ""
 "/// 以降で詳細なドキュメンテーションを記述します。コードブロックは三重のバッ"
 "ククォートで始まり、\n"
 "/// 暗黙的に`fn main()`と`extern crate <クレート名>`で囲われます。\n"
-"/// `doccomments`クレートをテストしたいときには、次のように記述します。\n"
+"/// `playground`クレートをテストしたいときには、次のように記述します。\n"
 "///\n"
 "/// ```\n"
-"/// let result = doccomments::add(2, 3);\n"
+"/// let result = playground::add(2, 3);\n"
 "/// assert_eq!(result, 5);\n"
 "/// ```\n"
 
@@ -16215,7 +16215,7 @@ msgid ""
 "/// # Examples\n"
 "///\n"
 "/// ```\n"
-"/// let result = doccomments::div(10, 2);\n"
+"/// let result = playground::div(10, 2);\n"
 "/// assert_eq!(result, 5);\n"
 "/// ```\n"
 "///\n"
@@ -16225,7 +16225,7 @@ msgid ""
 "///\n"
 "/// ```rust,should_panic\n"
 "/// // panics on division by zero\n"
-"/// doccomments::div(10, 0);\n"
+"/// playground::div(10, 0);\n"
 "/// ```\n"
 msgstr ""
 "/// 一般的に、ドキュメンテーションコメントは\n"
@@ -16236,7 +16236,7 @@ msgstr ""
 "/// # Examples\n"
 "///\n"
 "/// ```\n"
-"/// let result = doccomments::div(10, 2);\n"
+"/// let result = playground::div(10, 2);\n"
 "/// assert_eq!(result, 5);\n"
 "/// ```\n"
 "///\n"
@@ -16246,7 +16246,7 @@ msgstr ""
 "///\n"
 "/// ```rust,should_panic\n"
 "/// // ゼロで除算するとパニックします\n"
-"/// doccomments::div(10, 0);\n"
+"/// playground::div(10, 0);\n"
 "/// ```\n"
 
 #: src/testing/doc_testing.md:52
@@ -16291,7 +16291,7 @@ msgid ""
 "/// # // hidden lines start with `#` symbol, but they're still compilable!\n"
 "/// # fn try_main() -> Result<(), String> { // line that wraps the body "
 "shown in doc\n"
-"/// let res = doccomments::try_div(10, 2)?;\n"
+"/// let res = playground::try_div(10, 2)?;\n"
 "/// # Ok(()) // returning from try_main\n"
 "/// # }\n"
 "/// # fn main() { // starting main that'll unwrap()\n"
@@ -16305,7 +16305,7 @@ msgstr ""
 "/// ```\n"
 "/// # // 行頭に `#` を置くと行が隠されるが、コンパイルには成功します。\n"
 "/// # fn try_main() -> Result<(), String> { // ドキュメントの本体を囲う行\n"
-"/// let res = doccomments::try_div(10, 2)?;\n"
+"/// let res = playground::try_div(10, 2)?;\n"
 "/// # Ok(()) // try_mainから値を返します\n"
 "/// # }\n"
 "/// # fn main() { // unwrap()を実行します。\n"

po/zh.po

@@ -15454,22 +15454,22 @@ msgid ""
 "///\n"
 "/// The next lines present detailed documentation. Code blocks start with\n"
 "/// triple backquotes and have implicit `fn main()` inside\n"
-"/// and `extern crate <cratename>`. Assume we're testing `doccomments` "
-"crate:\n"
+"/// and `extern crate <cratename>`. Assume we're testing a `playground` library\n"
+"/// crate or using the Playground's Test action:\n"
 "///\n"
 "/// ```\n"
-"/// let result = doccomments::add(2, 3);\n"
+"/// let result = playground::add(2, 3);\n"
 "/// assert_eq!(result, 5);\n"
 "/// ```\n"
 msgstr ""
 "/// 第一行是函数的简要描述。\n"
 "///\n"
 "/// 接下来的几行是详细文档。代码块以三个反引号开始，\n"
 "/// 并隐含了 `fn main()` 函数和 `extern crate <cratename>` 声明。\n"
-"/// 假设我们正在测试 `doccomments` crate：\n"
+"/// 假设我们正在测试 `playground` crate：\n"
 "///\n"
 "/// ```\n"
-"/// let result = doccomments::add(2, 3);\n"
+"/// let result = playground::add(2, 3);\n"
 "/// assert_eq!(result, 5);\n"
 "/// ```\n"
 
@@ -15483,7 +15483,7 @@ msgid ""
 "/// # Examples\n"
 "///\n"
 "/// ```\n"
-"/// let result = doccomments::div(10, 2);\n"
+"/// let result = playground::div(10, 2);\n"
 "/// assert_eq!(result, 5);\n"
 "/// ```\n"
 "///\n"
@@ -15493,7 +15493,7 @@ msgid ""
 "///\n"
 "/// ```rust,should_panic\n"
 "/// // panics on division by zero\n"
-"/// doccomments::div(10, 0);\n"
+"/// playground::div(10, 0);\n"
 "/// ```\n"
 msgstr ""
 "/// 文档注释通常包含"示例"、"异常"和"错误"等部分。\n"
@@ -15503,7 +15503,7 @@ msgstr ""
 "/// # 示例\n"
 "///\n"
 "/// ```\n"
-"/// let result = doccomments::div(10, 2);\n"
+"/// let result = playground::div(10, 2);\n"
 "/// assert_eq!(result, 5);\n"
 "/// ```\n"
 "///\n"
@@ -15513,7 +15513,7 @@ msgstr ""
 "///\n"
 "/// ```rust,should_panic\n"
 "/// // 除以零会触发异常\n"
-"/// doccomments::div(10, 0);\n"
+"/// playground::div(10, 0);\n"
 "/// ```\n"
 
 #: src/testing/doc_testing.md:52
@@ -15549,7 +15549,7 @@ msgid ""
 "/// # // hidden lines start with `#` symbol, but they're still compilable!\n"
 "/// # fn try_main() -> Result<(), String> { // line that wraps the body shown "
 "in doc\n"
-"/// let res = doccomments::try_div(10, 2)?;\n"
+"/// let res = playground::try_div(10, 2)?;\n"
 "/// # Ok(()) // returning from try_main\n"
 "/// # }\n"
 "/// # fn main() { // starting main that'll unwrap()\n"
@@ -15563,7 +15563,7 @@ msgstr ""
 "/// ```\n"
 "/// # // 以 `#` 开头的行在文档中是隐藏的，但它们仍然可以编译！\n"
 "/// # fn try_main() -> Result<(), String> { // 这行包装了文档中显示的函数体\n"
-"/// let res = doccomments::try_div(10, 2)?;\n"
+"/// let res = playground::try_div(10, 2)?;\n"
 "/// # Ok(()) // 从 try_main 返回\n"
 "/// # }\n"
 "/// # fn main() { // 开始会调用 unwrap() 的 main 函数\n"

src/testing/doc_testing.md

@@ -11,10 +11,11 @@ as documentation tests.
 ///
 /// The next lines present detailed documentation. Code blocks start with
 /// triple backquotes and have implicit `fn main()` inside
-/// and `extern crate <cratename>`. Assume we're testing `doccomments` crate:
+/// and `extern crate <cratename>`. Assume we're testing a `playground` library
+/// crate or using the Playground's Test action:
 ///
 /// ```
-/// let result = doccomments::add(2, 3);
+/// let result = playground::add(2, 3);
 /// assert_eq!(result, 5);
 /// ```
 pub fn add(a: i32, b: i32) -> i32 {
@@ -28,7 +29,7 @@ pub fn add(a: i32, b: i32) -> i32 {
 /// # Examples
 ///
 /// ```
-/// let result = doccomments::div(10, 2);
+/// let result = playground::div(10, 2);
 /// assert_eq!(result, 5);
 /// ```
 ///
@@ -38,7 +39,7 @@ pub fn add(a: i32, b: i32) -> i32 {
 ///
 /// ```rust,should_panic
 /// // panics on division by zero
-/// doccomments::div(10, 0);
+/// playground::div(10, 0);
 /// ```
 pub fn div(a: i32, b: i32) -> i32 {
     if b == 0 {
@@ -58,7 +59,7 @@ running 0 tests
 
 test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
 
-   Doc-tests doccomments
+   Doc-tests playground
 
 running 3 tests
 test src/lib.rs - add (line 7) ... ok
@@ -84,7 +85,7 @@ and `unwrap` it in hidden `main`. Sounds complicated? Here's an example:
 /// ```
 /// # // hidden lines start with `#` symbol, but they're still compilable!
 /// # fn try_main() -> Result<(), String> { // line that wraps the body shown in doc
-/// let res = doccomments::try_div(10, 2)?;
+/// let res = playground::try_div(10, 2)?;
 /// # Ok(()) // returning from try_main
 /// # }
 /// # fn main() { // starting main that'll unwrap()