Update source/testing-your-html/index.html.md.erb

Co-authored-by: Oliver Byford <[email protected]>

source/testing-your-html/index.html.md.erb

@@ -49,7 +49,7 @@ Each object in the `fixtures` list is a different example of the component, wher
 - `html` is the HTML that GOV.UK Frontend outputs with these options
 - `hidden` is `true` if the fixture does not look or behave differently to the other fixtures provided
 
-Omit `hidden` fixtures from the list when you use fixtures for manual or visual regression testing.
+Do not include `hidden` fixtures when you use fixtures for manual or visual regression testing.
 
 For each example, pass `options` into your own macro and check the generated HTML matches `html`.