std/process/command: clarify Command::new behavior for programs with arguments

Author: jieyouxu

library/std/src/process.rs

@@ -606,6 +606,22 @@ impl Command {
     /// but this has some implementation limitations on Windows
     /// (see issue #37519).
     ///
+    /// [`Command::new`] is only intended to accept the path of the program. If you pass a program
+    /// path along with arguments such as `ls -l` for the program `ls` and argument `-l`, it will
+    /// try to search for `ls -l` literally.
+    ///
+    /// ```no_run (example demonstrating incorrect usage)
+    /// use std::process::Command;
+    ///
+    /// // Does not launch `ls`, will try to launch a program named `ls -l` literally.
+    /// Command::new("ls -l")
+    ///     .spawn()
+    ///     .unwrap();
+    /// ```
+    ///
+    /// The arguments need to be passed separately, such as via [`Command::arg`] or
+    /// [`Command::args`].
+    ///
     /// # Platform-specific behavior
     ///
     /// Note on Windows: For executable files with the .exe extension,