docs: remove unneeded hyphen (#480)

(In this instance, it doesn’t seem needed.)

Author: j9t

index.html

@@ -437,7 +437,7 @@ <h2 id="docconformance">
         Document conformance requirements for use of ARIA attributes in HTML
       </h2>
       <p>
-        The following table provides normative per-element document-conformance requirements for the 
+        The following table provides normative per-element document conformance requirements for the 
         use of ARIA markup in HTML documents. Additionally, it identifies the <a>implicit ARIA semantics</a> 
         that apply to [=HTML elements=]. The <a>implicit ARIA semantics</a> of these elements are defined 
         in [[html-aam-1.0|HTML AAM]].