update README template

data/unified_datasets/README_TEMPLATE.md

@@ -2,7 +2,7 @@
 
 - **Repository:** data link
 - **Paper:** paper link
-- **Leaderboard:** leaderboard link if any else empty
+- **Leaderboard:** leaderboard link if any else None
 - **Who transforms the dataset:** Name(email, e.g. xxx at gmail dot com)
 
 ### Dataset Summary

data/unified_datasets/multiwoz21/README.md

@@ -17,6 +17,7 @@ MultiWOZ 2.1 fixed the noise in state annotations and dialogue utterances. It al
   - Correct some grammar errors in the text, mainly following `tokenization.md` in MultiWOZ_2.1.
   - Normalize slot name and value. See `normalize_domain_slot_value` function in `preprocess.py`.
   - Correct some non-categorical slots' values and provide character level span annotation.
+  - Concatenate multiple values in user goal & state using `|`.
 - **Annotations:**
   - user goal, dialogue acts, state.