Fix invalid controlled identifier document reference.

index.html

@@ -1282,10 +1282,10 @@ <h2>Verification Methods</h2>
 Note, however, that for [=verification methods=], it is only
 an assertion made by the `controller` of the [=controlled identifier document=],
 and this assertion is not necessarily true, i.e., it may be false.
-To ensure that a [=verification method=] 
+To ensure that a [=verification method=]
 is bound to a particular [=controller=],
 one must go from the expression of the [=verification method=]
-to its [=controlled-identifier-document=],
+to its [=controlled identifier document=],
 and then verify that the latter contains references to both
 the [=verification method=] and its [=controller=]. See Section [[[#retrieve-verification-method]]] for an algorithm that ensures that a proper binding is verified.
             </p>