Update table docs and example

Author: NicolaSaunders

design-system-templates/components/table.html.twig

@@ -4,19 +4,19 @@
 	</caption>
 	<thead>
 	<tr>
+		<td></td>
 		<th scope="col">Column header 1</th>
 		<th scope="col">Column header 2</th>
-		<th scope="col">Column header 3</th>
 	</tr>
 	</thead>
 	<tbody>
 	<tr>
-		<th scope="row">Row 1 header</th>
+		<th scope="row">Row header 1</th>
 		<td>Row 1, cell 2</td>
 		<td>Row 1, cell 3</td>
 	</tr>
 	<tr>
-		<th scope="row">Row 2 header</th>
+		<th scope="row">Row header 2</th>
 		<td>Row 2, cell 2</td>
 		<td>Row 2, cell 3</td>
 	</tr>

docs/styles/tables.md

@@ -4,7 +4,7 @@ The table markup must include column and/or row headers (`<th>`). Some screen re
 
 Use the attributes `scope="col"` and `scope="row"` to differentiate between column and row headers respectively.
 
-Where there are both column and row headers, do not leave the first header cell empty as this can produce unexpected behaviour.
+Where there are both column and row headers, do not use an empty table header `<th>` in the first column as this can produce unexpected behaviour. An empty table cell `<td>` is acceptable, if necessary (note the example table which follows).
 
 Use a `<caption>` to label the table correctly. A heading element can be used within the caption if desired.