Add sections on native interactive elements and tab order.

style_guides/html_style_guide.md

@@ -62,4 +62,13 @@ described element can point to with the `aria-describedby` attribute. For exampl
 <button aria-describedby="visualizationsTooltip">
  Visualizations
 </button>
-```
+```
+
+### Use `button` and `a` to make interactive elements keyboard-accessible
+
+If something is meant to be clickable, favor using a `button` or `a` tag before over the `kui-accessible-click` directive or `KuiKeyboardAccessible` component. These tools are useful as they augment non-clickable elements with `onkeypress` and `onkeyup` handlers, allowing non-clickable elements to become keyboard accessible. However, `button` and `a` tags provide this functionality natively.
+
+### Use `tabindex` to make elements tabbable
+
+When added to the tab order, elements become focusable via non-sticky-mode keyboard navigation.
+To add an element to the tab order, you must add an `id` attribute as well as a `tabindex` attribute. If you don't know which number to use for the tab index, or if you simply want to add it to the general flow of the document, use `tabindex="0"`.