DOC Document changes to usage of font-icon CSS classes (#811)

Author: GuySartorelli

en/08_Changelogs/6.2.0.md

@@ -23,6 +23,18 @@ title: 6.2.0 (unreleased)
 - In the `silverstripe/linkfield` module, the `.link-picker__delete` element has been moved up a level so that it is now a child of `.link-picker__link` and its tag has changed from `span` to `button`.
 - The viewport meta tag no longer includes `maximum-scale=1.0`, which prevented users from zooming in on mobile devices. It now includes `initial-scale=1.0` instead.
 
+#### Changes to usage of `font-icon-*` CSS classes
+
+The `font-icon-*` CSS classes used to add icons through the CMS use a font to render normal characters as icons.
+
+This is very useful for sighted users, but represents a problem for screen reader users, since screen readers want to read the icons like normal characters. For example, the `font-icon-search` icon uses the character "s", so screen readers will read out "s" whenever they encounter that icon.
+
+In many places in the CMS markup we have added `aria-hidden="true"` to elements using `font-icon-*` CSS classes. Often this has required removing the CSS class from the element it was on, and adding it instead to a child `<span>` element. We have also changed some `<i>` elements into `<span>` elements.
+
+If you were relying on an element having a CSS class that starts with `font-icon-` in the CMS, please review your code, as the CSS class you're looking for may be on a child element now.
+
+If your own code uses a `font-icon-*` CSS class, we recommend adding `aria-hidden="true"` if the icon is purely decorative. If the icon is needed to present information that isn't presented with text, we recommend moving the icon into a child element, and adding an `aria-label` attribute to your parent element so screen readers have the same context as sighted users.
+
 ### Other new features and enhancements {#other-new}
 
 - [`Hierarchy::duplicateWithChildren()`](api:SilverStripe\ORM\Hierarchy\Hierarchy::duplicateWithChildren()) used to set new sort values for duplicated children - it now uses the sort values from the original records.