doc: make doc version selector more obvious

Move the doc version selector menu higher on the left nav to make it
more visible (from its prior bottom of the nav menu)

Signed-off-by: David B. Kinder <david.b.kinder@intel.com>

doc/_templates/aversions.html

@@ -0,0 +1,25 @@
+{# Add rst-badge after rst-versions for small badge style. #}
+  <div class="rst-versions" data-toggle="rst-versions" role="note" aria-label="versions">
+    <span class="rst-current-version" data-toggle="rst-current-version">
+      <span class="fa fa-book"> Project ACRN</span>
+      v: {{ current_version }}
+      <span class="fa fa-caret-down"></span>
+    </span>
+    <div class="rst-other-versions">
+      <dl>
+        <dt>{{ _('Document Versions') }}</dt>
+        {% for slug, url in versions %}
+          <dd><a href="{{ url }}">{{ slug }}</a></dd>
+        {% endfor %}
+      </dl>
+      <dl>
+        <dt>{{ _('projectacrn.org links') }}</dt>
+          <dd>
+            <a href="https://www.projectacrn.org/">Project Home</a>
+          </dd>
+          <dd>
+            <a href="https://github.com/projectacrn/acrn-hypervisor/wiki">Wiki</a>
+          </dd>
+      </dl>
+    </div>
+  </div>