[css-text] Update test coverage info

Author: frivoal

css-text-3/Overview.bs

@@ -3120,7 +3120,8 @@ Line Breaking Details</h3>
 
             <wpt>
               line-break/line-break-loose-015.xht
-              line-break/line-break-normal-015.xht
+              line-break/line-break-normal-015a.xht
+              line-break/line-break-normal-015b.xht
               line-break/line-break-strict-015.xht
               i18n/ja/css-text-line-break-ja-in-loose.html
               i18n/ja/css-text-line-break-ja-in-normal.html