DOCS-878 fix nav to parents (choose closest parent not "highest")

Author: Ed Costello

themes/mongodb/layout.html

@@ -103,7 +103,7 @@
 <li id="btnvpr"><a href="{{ prev.link|e }}" title="Previous Section: {{ prev.title|striptags|e }}">&lt; &nbsp; {{ prev.title|striptags|e }}</a></li>
 {%- endif %}
 {%- if parents %}
-<li id="btnvup"><a href="{{ parents[0].link|e }}" title="Parent Section: {{ parents[0].title|striptags|e }}" >&#47;&#92;&nbsp; {{ parents[0].title|striptags|e }}</a></li>
+<li id="btnvup"><a href="{{ parents[-1].link|e }}" title="Parent Section: {{ parents[-1].title|striptags|e }}" >&#47;&#92;&nbsp; {{ parents[-1].title|striptags|e }}</a></li>
 {%- endif %}
 {%- if next %}
 <li id="btnvnx"><a href="{{ next.link|e }}" title="Next Section: {{ next.title|striptags|e }}">{{ next.title|striptags|e }} &nbsp;&gt;</a></li>