[refs #320] Reorder attribute order of <button> element

As per our [coding standards](/docs/contributing/coding-standards.md#html)

packages/components/header/template.njk

@@ -116,7 +116,7 @@
               <label class="nhsuk-u-visually-hidden" for="search-field">Search the NHS website</label>
               <div class="autocomplete-container" id="autocomplete-container"></div>
               <input class="nhsuk-search__input" id="search-field" name="search-field" type="search" placeholder="Search" autocomplete="off" >
-              <button type="submit" class="nhsuk-search__submit">
+              <button class="nhsuk-search__submit" type="submit">
                 <svg class="nhsuk-icon nhsuk-icon__search" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" aria-hidden="true" focusable="false">
                   <path d="M19.71 18.29l-4.11-4.1a7 7 0 1 0-1.41 1.41l4.1 4.11a1 1 0 0 0 1.42 0 1 1 0 0 0 0-1.42zM5 10a5 5 0 1 1 5 5 5 5 0 0 1-5-5z"></path>
                 </svg>