fix typo: shell_beep->shell_bell

commit 1ac759acb58d9715c71b7b37c3f32c03bef270e9
Author: Julie Zelenski <[email protected]>
Date:   Thu Nov 7 11:59:43 2024 -0800

    fix typo: shell_beep->shell_bell

Author: zelenski

assignments/assign5/README.md

@@ -577,7 +577,7 @@ cs107e rocks
   3 history
     ```
 
-    Implement the up and down arrow keys to access commands from the history. Typing an up arrow changes the current line to display the command from the history that is previous to the one on the current line. Typing a down arrow changes the current line to display the command that ran _after_ the one on the current line, or whatever the user had typed until he/she typed up. Use the `shell_beep` when the user tries to move beyond either end of the history.
+    Implement the up and down arrow keys to access commands from the history. Typing an up arrow changes the current line to display the command from the history that is previous to the one on the current line. Typing a down arrow changes the current line to display the command that ran _after_ the one on the current line, or whatever the user had typed until he/she typed up. Call `shell_bell` to alert the user if they try to move beyond either end of the history.
 
     What other history features will be handy? `!!` to repeat the last command? `!po` to repeat the most recent command matching the specified prefix `po`?