Allow translations for strings in relations.html (#104)

Co-authored-by: Adam Turner <[email protected]>

Author: bitfidus

alabaster/relations.html

@@ -1,16 +1,16 @@
 <div class="relations">
-<h3>Related Topics</h3>
+<h3>{{ _('Related Topics') }}</h3>
 <ul>
-  <li><a href="{{ pathto(master_doc) }}">Documentation overview</a><ul>
+  <li><a href="{{ pathto(master_doc) }}">{{ _('Documentation overview') }}</a><ul>
   {%- for parent in parents %}
   <li><a href="{{ parent.link|e }}">{{ parent.title }}</a><ul>
   {%- endfor %}
     {%- if prev %}
-      <li>Previous: <a href="{{ prev.link|e }}" title="{{ _('previous chapter')
+      <li>{{ _('Previous') }}: <a href="{{ prev.link|e }}" title="{{ _('previous chapter')
         }}">{{ prev.title }}</a></li>
     {%- endif %}
     {%- if next %}
-      <li>Next: <a href="{{ next.link|e }}" title="{{ _('next chapter')
+      <li>{{ _('Next') }}: <a href="{{ next.link|e }}" title="{{ _('next chapter')
         }}">{{ next.title }}</a></li>
     {%- endif %}
   {%- for parent in parents %}