Fix version dropdown

In subdirectories, the version dropdown is incorrect for the Latest
entry, it produces:
<div class="version-dropdown-content">
                    <p><a href="../latest/" rel="nofollow">Latest</a></p>
                    <p><a href="../../stein" rel="nofollow">stein</a></p>
                    <p><a href="../../rocky" rel="nofollow">rocky</a></p>

Notice the "../" instead of "../..". This breaks the "latest" link on
documents such as https://docs.openstack.org/manila/latest/admin/index.html
where "latest" links then to https://docs.openstack.org/manila/latest/latest/

Fix this by using the same logic for latest as for the other versions,
there's no need to special case it.

Change-Id: I6b0fe830f764ce7dde24cff9c7b84c6a894ca408

openstackdocstheme/ext.py

@@ -84,9 +84,9 @@ def _get_other_versions(app):
         interesting_series = all_series
 
     # Reverse the list because we want the most recent to appear at
-    # the top of the dropdown. The "latest" release is added to the
-    # front of the list by the theme so we do not need to add it
-    # here.
+    # the top of the dropdown. Add the "latest" release to the
+    # front of the list.
+    interesting_series.append("latest")
     interesting_series.reverse()
     return interesting_series
 

openstackdocstheme/theme/openstackdocs/layout.html

@@ -46,7 +46,6 @@ ga('send', 'pageview');
             <div class="version-dropdown">
             <span>{{ _('version') }}</span>
               <div class="version-dropdown-content">
-                    <p><a href="../latest/" rel="nofollow">Latest</a></p>
                   {%- for ver in other_versions: %}
                     <p><a href="../{{pathto(ver, 1) }}" rel="nofollow">{{ ver }}</a></p>
                   {%- endfor %}