[css-fonts-4] Delete broken reference to OPENTYPE-FONT-GUIDE, fix #9067

Author: svgeesus

css-fonts-4/Overview.bs

@@ -4515,8 +4515,6 @@ Glyph selection and positioning</h3>
 	(such as text transformation, text orientation and text alignment)
 	is described in [[css-text-3#order]].
 
-	For a good visual overview of these features,
-	see the [[OPENTYPE-FONT-GUIDE]].
 	For a detailed description of glyph processing
 	for OpenType fonts,
 	see [[WINDOWS-GLYPH-PROC]].