Change "Read more" to "See posts" on author summary card

I never noticed this; you can read more of an article, but it doesn't
really make any sense to "Read more" on an author.

layouts/authors/summary.html

@@ -13,6 +13,6 @@
     {{ end }}
 
     <div class="summary-card-readmore">
-        <a href="{{ .Permalink }}">{{ i18n "read_more" }} &rarr;</a>
+        <a href="{{ .Permalink }}">{{ i18n "see_posts" }} &rarr;</a>
     </div>
 </article>