corporate_identity: fix markup in table of content

There was opening and closing tags mismatch:
    <div><a href="#references1_anchor">References</div></a>
2 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
failed ERP5.PerformanceTest-Master

00:26:11

passed SlapOS.Eggs.UnitTest-Master.Python2

00:13:06