Update documentation

docs/docs/configuration/client.rst

@@ -107,11 +107,10 @@ Enable or disable voting feature on the client side.
 data-isso-id
 ------------
 
-Broken – do not use. https://github.com/posativ/isso/issues/27
-
-Set a custom thread id, defaults to current URI. If you use a comment counter,
-add this attribute to the link tag, too.
+Set a custom thread id, defaults to current URI. This attribute needs
+to be used with the data-title attribute in order to work.
+If you use a comment counter, add this attribute to the link tag, too.
 
 .. code-block:: html
 
-    <section data-isso-id="test.abc" id="isso-thread"></section>
+    <section data-title="Yay!" data-isso-id="test.abc" id="isso-thread"></section>