fixed URL to qiskit.org web site embedded in HTML documents
{%- block header %}
<div id="head" class="head">
- <a href="https://qiskit.org/aqua/chemistry">Qiskit Aqua Chemistry</a>
+ <a href="https://qiskit.org/aqua">Qiskit Aqua</a>
</div>
{%- endblock %}
