Update JavaDoc to clarify redo keybinding on macOS

Updated the JavaDoc to reflect that the redo command on macOS is {@code Shift + Cmd + Z},
not {@code Cmd + Y}, and may vary on other platforms. This ensures the documentation is
accurate and aligns with the actual keybindings.

No functional code changes were made.

Author: yehiarasheed

app/src/processing/app/ui/Editor.java

@@ -1937,7 +1937,8 @@ public void handleIndentOutdent(boolean indent) {
    * <p>This method ensures proper selection updates and handles edge cases like moving
    * the first or last line.</p>
    * <p>This operation is undo/redoable, allowing the user to revert the action using
-   * {@code Ctrl/Cmd + Z} (Undo) and redo with {@code Ctrl/Cmd + Y} (Redo).</p>
+   * {@code Ctrl/Cmd + Z} (Undo). Redo functionality is available through the
+   * keybinding {@code Ctrl/Cmd + Z} on Windows/Linux and {@code Shift + Cmd + Z} on macOS.</p>
    *
    * @param moveUp {@code true} to move the selection up, {@code false} to move it down.
    */