[css-text-3] Use the same wording in both paragraphs.

Author: fantasai

css-text-3/Overview.bs

@@ -5613,7 +5613,7 @@ Identifying the Content Writing System</h2>
 	for languages strongly associated with a single writing system:
 	instead that writing system is expected to be implied
 	when no other is specified.
-	IANA maintains a database of various languages’ default writing systems
+	IANA maintains a database of various languages’ most common writing system
 	via the <code>Suppress-Script</code> field in its
 	<a href="https://www.iana.org/assignments/language-subtag-registry/language-subtag-registry">language subtag registry</a>
 	for this purpose.