[DOC] Another example for spawn (#8575)

process.c

@@ -4952,19 +4952,25 @@ rb_f_system(int argc, VALUE *argv, VALUE _)
  *
  *  Argument +exe_path+ is one of the following:
  *
- *  - The string path to an executable to be called.
+ *  - The string path to an executable to be called:
- *  - A 2-element array containing the path to an executable
- *    and the string to be used as the name of the executing process.
  *
- *  Example:
+ *      spawn('/usr/bin/date') # Path to date on Unix-style system.
- *
+ *      Process.wait
- *    spawn('/usr/bin/date') # => 799198 # Path to date on Unix-style system.
- *    Process.wait           # => 799198
  *
  *    Output:
  *
  *      Thu Aug 31 10:06:48 AM CDT 2023
  *
+ *  - A 2-element array containing the path to an executable
+ *    and the string to be used as the name of the executing process:
+ *
+ *      pid = spawn(['sleep', 'Hello!'], '1') # 2-element array.
+ *      p `ps -p #{pid} -o command=`
+ *
+ *    Output:
+ *
+ *      "Hello! 1\n"
+ *
  *  Ruby invokes the executable directly, with no shell and no shell expansion.
  *
  *  If one or more +args+ is given, each is an argument or option