add lang clarification to translatable attributes section. (#1690)

* add lang clarification to translatable attributes section.
Resolves #1365
* Removing accidental whitespace line break
* editorial nit
* carmacleod suggestion: 'value' -> 'attribute value'
Co-authored-by: Carolyn MacLeod <Carolyn_MacLeod@ca.ibm.com>
* Change references
Co-authored-by: Carolyn MacLeod <Carolyn_MacLeod@ca.ibm.com>
Co-authored-by: James Nurthen <jnurthen@users.noreply.github.com>

Author: 3 people

index.html

@@ -10329,9 +10329,10 @@ <h4>Example Attribute Usage</h4>
 			</section>
 		</section>
 	</section>
-	<section>
-		<h2>Translatable States and Properties</h2>
-		<p>The HTML specification states that other specifications can define <a href="https://html.spec.whatwg.org/multipage/dom.html#translatable-attributes">translatable attributes</a>. In order to be understandable by assistive technology users, the values of the following <a>states</a> and <a>properties</a> are <a href="https://html.spec.whatwg.org/multipage/dom.html#translatable-attributes">translatable attributes</a> and should be translated when a page is localized:</p>
+	<section data-cite="HTML">
+		<h2>Translatable Attributes</h2>
+		<p>The HTML specification states that other specifications can define <a data-cite="html/dom.html#translatable-attributes">translatable attributes</a>. The source translation language of each attribute value is defined by use of the [^html-global/lang^] attribute on the element or its ancestor elements.</p>
+		<p>To be understandable by assistive technology users, the values of the following <a>states</a> and <a>properties</a> are <a data-cite="html/dom.html#translatable-attributes">translatable attributes</a> and should be translated when a page is localized:</p>
 		<ul>
 			<li><pref>aria-label</pref></li>
 			<li><pref>aria-placeholder</pref></li>