Merge pull request #250 from alphagov/update-docs-for-skiplink

Add docs for adding tabindex="-1" to fix the skiplink

docs/usage.md

@@ -8,6 +8,13 @@ Refer to the table of [template blocks](./docs/template-blocks.md) and their def
 
 The [govuk_template sets a skip link](https://github.com/alphagov/govuk_template/blob/master/source/views/layouts/govuk_template.html.erb#L64-L68) to `#content`, but doesn't provide an element with `id="content"`. You'll need to add `id="content"` to your main content area, to ensure the skip link will work.
 
+    <main id="content" role="main" tabindex="-1">
+
+It is recommended to use the main element, with a role of main (to support older assistive technology), also `tabindex="-1"` is required to fix the issue [with focus in Safari](https://bugs.chromium.org/p/chromium/issues/detail?id=37721).
+
+You can see an [example of this working in GOV.UK elements](https://github.com/alphagov/govuk_elements/blob/master/app/views/index.html#L9).
+
+
 ## Propositional title and navigation
 
 You can get a propositional title and navigation by setting the content for `header_class` to `with-proposition` and `proposition_header` in the form: