Add description to card metadata (#1)

- Add description to card metadata (a14b668b612263dc9817292ce583aaef88bd840f)

README.md

@@ -1,6 +1,6 @@
 ---
 title: BERT Score
-emoji: 🤗 
+emoji: 🤗
 colorFrom: blue
 colorTo: red
 sdk: gradio
@@ -8,10 +8,26 @@ sdk_version: 3.0.2
 app_file: app.py
 pinned: false
 tags:
-- evaluate
-- metric
----
+  - evaluate
+  - metric
+description: >-
+  BERTScore leverages the pre-trained contextual embeddings from BERT and
+  matches words in candidate and reference
+
+  sentences by cosine similarity.
+
+  It has been shown to correlate with human judgment on sentence-level and
+  system-level evaluation.
+
+  Moreover, BERTScore computes precision, recall, and F1 measure, which can be
+  useful for evaluating different language
 
+  generation tasks.
+
+
+  See the project's README at https://github.com/Tiiiger/bert_score#readme for
+  more information.
+---
 # Metric Card for BERT Score
 
 ## Metric description