docs(derive): Add help text

examples/tutorial_derive/04_01_enum.md

@@ -4,11 +4,31 @@ A simple to use, efficient, and full-featured Command Line Argument Parser
 
 Usage: 04_01_enum_derive[EXE] <MODE>
 
+Arguments:
+  <MODE>
+          What mode to run the program in
+
+          Possible values:
+          - fast: Run swiftly
+          - slow: Crawl slowly but steadily
+
+Options:
+  -h, --help
+          Print help information (use `-h` for a summary)
+
+  -V, --version
+          Print version information
+
+$ 04_01_enum_derive -h
+A simple to use, efficient, and full-featured Command Line Argument Parser
+
+Usage: 04_01_enum_derive[EXE] <MODE>
+
 Arguments:
   <MODE>  What mode to run the program in [possible values: fast, slow]
 
 Options:
-  -h, --help     Print help information
+  -h, --help     Print help information (use `--help` for more detail)
   -V, --version  Print version information
 
 $ 04_01_enum_derive fast

examples/tutorial_derive/04_01_enum.rs

@@ -10,7 +10,11 @@ struct Cli {
 
 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, ValueEnum)]
 enum Mode {
+    /// Run swiftly
     Fast,
+    /// Crawl slowly but steadily
+    ///
+    /// This paragraph is ignored because there is no long help text for possible values.
     Slow,
 }