remove data-isso-id from documentation, it usually doesn't work as expected

docs/docs/configuration/client.rst

@@ -124,14 +124,3 @@ For example, the value `"-5,5"` will cause each `isso-comment` to be given one o
 - `isso-vote-level-2` for scores of `5` and greater
 
 These classes can then be used to customize the appearance of comments (eg. put a star on popular comments)
-
-data-isso-id
-------------
-
-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-title="Yay!" data-isso-id="test.abc" id="isso-thread"></section>