add annotation guidelines

README.md

@@ -172,6 +172,8 @@ In the second approach, the passage candidates were proposed by the BM25 retriev
 
 In both cases, all proposed question-passage pairs were manually verified by the annotators.
 
+We release the annotation guidelines [here](https://docs.google.com/document/d/1LDW7EJFH0bm-FRlxM_uHb0mqJzKHiewOFBHe5qZnTW8/edit?usp=sharing).
+
 #### Who are the annotators?
 
 The annotation team consisted of 16 annotators, all native Polish