Fix grammar

Author: Hassanmir92

app/views/shared/eligible_region_content_components/_proof_of_work_history.html.erb

@@ -26,7 +26,7 @@
     <% if FeatureFlags::FeatureFlag.active?(:email_domains_for_referees) %>
       <li>have an email address that uses the institution’s domain, for example, name@institution.edu</li>
     <% end %>
-    <li>be a senior member of staff that is still working at this institution (either a headteacher/principal, an assistant/deputy head, or a institution business manager)</li>
+    <li>be a senior member of staff that is still working at this institution (either a headteacher/principal, an assistant/deputy head, or an institution business manager)</li>
     <li>be able to provide a reference in English</li>
     <li>only comment on teaching work that you did after becoming a qualified teacher</li>
   </ul>