Modified descriptions are only allowed to be populated into an export template. The source file will always retain the original section description, regardless of any changes made to it.
<% if (previousArticle) { %>
<% } %>
<% if (previousTitle) { %>
<% } %><% if (nextArticle) { %> <%= previousTitle %>
<% } %> <%= previousArticle.title %><% if (nextTitle) { %>
<% } %>