调整文档侧边栏的显示

docs/source/_templates/versions.html

@@ -2,7 +2,7 @@
 <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"> Other Versions</span>
-    v: {{ current_version.name }}
+    {{ current_version.name }}
     <span class="fa fa-caret-down"></span>
   </span>
   <div class="rst-other-versions">