Use reading width for school moves introduction

Author: paulrobertlloyd

app/views/school_moves/index.html.erb

@@ -1,13 +1,10 @@
 <%= h1 "School moves", size: "xl" %>
 
-<div class="nhsuk-grid-row">
-  <div class="nhsuk-grid-column-two-thirds">
-    <p>When imported records or a new consent response indicates that a child has changed
-      school, Mavis flags this as a school move.</p>
-    <p>You can then review the new information and confirm the school move or ignore it.</p>
+<div class="nhsuk-u-reading-width">
+  <p>When imported records or a new consent response indicates that a child has changed school, Mavis flags this as a school move.</p>
+  <p>You can then review the new information and confirm the school move or ignore it.</p>
 
-    <%= govuk_button_to "Download records", school_move_exports_path, class: "app-button--secondary nhsuk-u-margin-bottom-5" %>
-  </div>
+  <%= govuk_button_to "Download records", school_move_exports_path, class: "app-button--secondary nhsuk-u-margin-bottom-5" %>
 </div>
 
 <% if @school_moves.any? %>