Update content following review with Karl

app/templates/views/edit-sms-template.html

@@ -16,7 +16,7 @@
     ) }}
 
     {% if current_service.prefix_sms %}
-      {% set content_hint = 'All messages will start with your service name' %}
+      {% set content_hint = 'Your message will start with your service name' %}
     {% endif %}
 
     {% call form_wrapper() %}