Update README.md

README.md

@@ -51,7 +51,7 @@ The corpus is released in JSONL format. Each document contains the following att
         "url": "document url", 
         "title": "document title", 
         "author": "document author if known, null otherwise", 
-        "date": "publication date in yyyy-mm-dd format", 
+        "date": "publication date in yyyy[-mm-dd[Thh:mm:ssZ]] format", 
         "text": "document content, ready to use raw text. Title text (for news and articles) is included as well.",
         "domain": "document domain. one of ['news', 'administrative', 'wikipedia', 'science', 'subtitles', 'literature', 'videogames']"
 }