Comment icon missing from customize toolbar dialog

Where is the comment icon in the Customize Toolbar dialog window? It’s missing in both the Format Toolbar and Main Toolbar selections. I know the “add comment” option is available in the dropdown list with the paperclip icon in the toolbar, but I want to access the comment icon quickly by placing it directly in the main toolbar. How can I do this?

In the Formatting Toolbar:


Ah! I must have missed it. Thanks!