Add a new heading for clarity

ch01_starting_vim.md

@@ -30,6 +30,8 @@ There are several ways to exit Vim. The most common one is to type:
 
 You can type `:q` for short. That command is a command-line mode command (another one of Vim modes). If you type `:` in normal mode, the cursor will move to the bottom of the screen where you can type some commands. You will learn about the command-line mode later in chapter 15. If you are in insert mode, typing `:` will literally produce the character ":" on the screen. In this case, you need to switch back to normal mode. Type `<Esc>` to switch to normal mode. By the way, you can also return to normal mode from command-line mode by pressing `<Esc>`. You will notice that you can "escape" out of several Vim modes back to normal mode by pressing `<Esc>`.
 
+## Saving A File
+
 To save your changes, type:
 
 ```