[css-font-loading-3] Mention document.fonts in the intro, to make it easier to find. Fixes w3c#6125

Author: tabatkins

css-font-loading-3/Overview.bs

@@ -33,7 +33,8 @@ Introduction</h2>
 	as the user agent finally notices a usage and begins downloading and parsing the font file.
 
 	This specification defines a scripting interface to font faces in CSS,
-	allowing font faces to be easily created and loaded from script.
+	allowing font faces to be easily created (via the {{FontFace}} interface)
+	and loaded from script (via [[#font-face-source|document.fonts]]).
 	It also provides methods to track the loading status of an individual font,
 	or of all the fonts on an entire page.