readme: fix example

README.md

@@ -61,7 +61,7 @@ Here's an example of an annotated document:
 ```txt
 TOKEN	NE-COARSE-LIT	MISC
 
--DOCSTART-	O
+-DOCSTART-	O	_
 
 # onb:id = ONB_wrz_17800701
 # onb:image_link = https://anno.onb.ac.at/cgi-content/anno?aid=wrz&datum=17800701&seite=12
@@ -79,7 +79,7 @@ legten	O	_
 sogleich	O	_
 ```
 
-Note: we include a `-DOCSTART-` information to e.g. allow document-level features for NER as proposed in the [FLERT](https://arxiv.org/abs/2011.06993) paper.
+Note: we include a `-DOCSTART-` marker to e.g. allow document-level features for NER as proposed in the [FLERT](https://arxiv.org/abs/2011.06993) paper.
 
 ## Dataset Splits