[MINOR][DOC] Add docker page link to site header

Author: j143

docs/_includes/header.html

@@ -45,6 +45,7 @@
                         <li><a href=".{% if page.path contains 'site' %}/..{% endif %}/site/run">Standalone Guide</a></li>
                         <li><a href=".{% if page.path contains 'site' %}/..{% endif %}/site/gpu">GPU Guide</a></li>
                         <li><a href=".{% if page.path contains 'site' %}/..{% endif %}/site/native-backend">Native Backend (BLAS)</a></li>
+                        <li><a href=".{% if page.path contains 'site' %}/..{% endif %}/site/docker">Run with Docker</a></li>
                         <li class="divider"></li>
                         <li><b>Language Guides:</b></li>
                         <li><a href=".{% if page.path contains 'site' %}/..{% endif %}/site/dml-language-reference.html">DML Language Reference</a></li>