Amend documentation to detail how email Opt-Out categories are used

I find some of the documentation to be very lacking and difficult to navigate - often having to click around at several different pages on the same topic struggling to find the right source.

I'm attempting to test out the custom email opt-out categories feature and the documentation does not describe nor link to any information about how specifically to use the categories. I thought maybe it would be a field value required in a query, but first checked Program settings, though it's actually a setting within the email template. I would think there would be a comment or crosslink to this page from the opt-out page (also, if you notice the breadcrumb, it's Standard Outreaches >JO templates, but templates are independent of Outreach type).