docs/theme: Make sidebar border less intrusive

Only on the right, much lighter, no radius

doc_src/python_docs_theme/static/pydoctheme.css

@@ -59,8 +59,8 @@ form.inline-search input[type="submit"] {
 
 div.sphinxsidebar {
     background-color: #eeeefa;
-    border: 1px solid;
-    border-radius: 5px;
+    border-right: 1px solid #ccc;
+    border-radius: 0px;
     line-height: 130%;
     font-size: smaller;
     overflow: auto;