Add description to card metadata

Returns the rate at which the input predicted strings exactly match their references, ignoring any strings input as part of the regexes_to_ignore list.

README.md

@@ -1,6 +1,6 @@
 ---
 title: Exact Match
-emoji: 🤗 
+emoji: 🤗
 colorFrom: blue
 colorTo: red
 sdk: gradio
@@ -8,10 +8,12 @@ sdk_version: 3.0.2
 app_file: app.py
 pinned: false
 tags:
-- evaluate
-- metric
+  - evaluate
+  - metric
+description: >-
+  Returns the rate at which the input predicted strings exactly match their
+  references, ignoring any strings input as part of the regexes_to_ignore list.
 ---
-
 # Metric Card for Exact Match