[css-fonts-4] Link to Graphite v3 not v2

Author: svgeesus

css-fonts-4/Overview.bs

@@ -6683,7 +6683,7 @@ The System Font is the font which is used by the ''system-ui'' <a href="#system-
 	<code>Feat </code> and
 	<code>Sill </code> tables
 	as documented in the
-	<a href="http://scripts.sil.org/cms/sites/nrsi/media/GraphiteBinaryFormat_pdf.pdf">Graphite Table Format</a>.
+	<a href="https://scripts.sil.org/cms/scripts/render_download.php?site_id=nrsi&format=file&media_id=GraphiteBinaryFormat_3_0&filename=GraphiteBinaryFormat_3_0.pdf">Graphite Table Format</a>.
     The section on [[#font-rend-props]] describes properties that interact with these facilities.
 
     The 'variations' technology refers to the support of font variations,