Update travel advice callout box for country pages.

This is due to the new tier 4 guidance.

app/views/content_items/travel_advice.html.erb

@@ -27,11 +27,11 @@
       <div class="travel-advice-notice__content">
         <p class="govuk-body">
           <strong>
-            Travel in your area, including international travel, may be restricted because of domestic regulations. Different rules apply in <a href="/guidance/local-restriction-tiers-what-you-need-to-know">England</a>, <a href="https://www.gov.scot/coronavirus-covid-19/">Scotland</a>, <a href="https://gov.wales/coronavirus-regulations-guidance">Wales</a> and <a href="https://www.nidirect.gov.uk/articles/coronavirus-covid-19-regulations-guidance-what-restrictions-mean-you">Northern Ireland</a>. Follow all the rules that apply to you.
+            Following identification of a new variant of the virus, international travel from your area may be increasingly restricted because of domestic regulations. Different rules apply in <a href="/guidance/local-restriction-tiers-what-you-need-to-know">England</a>, <a href="https://www.gov.scot/coronavirus-covid-19/">Scotland</a>, <a href="https://gov.wales/coronavirus-regulations-guidance">Wales</a> and <a href="https://www.nidirect.gov.uk/articles/coronavirus-covid-19-regulations-guidance-what-restrictions-mean-you">Northern Ireland</a>. For example, those in Tier 4 areas in England will not be permitted to travel abroad apart from limited exceptions, such as work purposes. Follow all the rules that apply to you.
           </strong>
         </p>
         <p class="govuk-body">
-          Other countries may close borders, restrict movement or bring in new quarantine rules with little warning. <a href="/guidance/travel-advice-novel-coronavirus">Check our advice</a> on things to consider, and be prepared to stay overseas longer than planned.
+          Other countries have closed borders, and may restrict movement or bring in new quarantine rules with little warning. <a href="/guidance/travel-advice-novel-coronavirus">Check our advice</a> on things to consider, and be prepared to stay overseas longer than planned.
         </p>
         <p class="govuk-body">
           Before you return to the UK you must <a href="/provide-journey-contact-details-before-travel-uk">provide your journey and contact details</a>. Also check if you need to <a href="/uk-border-control">self isolate</a>.