mention 19.3 in the OCR guide

Author: tony-xlh

_articles/extended-usage/ocr.md

@@ -480,7 +480,7 @@ The OCR add-on supports two kinds of searchable PDF output.
 
 OCR Basic and OCR Pro are previous OCR add-ons, which are deprecated in v16.2. But they are still usable in the latest version.
 
-To differentiate from previous versions, the new OCR uses `OCRKit` as the namespace.
+To differentiate from previous versions, the new OCR added since v19.3 uses `OCRKit` as the namespace.
 
 ### Why I Cannot Load Saved PDF Files