FIX: add a translation for reaction notification (#10316)

Follow https://github.com/discourse/discourse/pull/10315

config/locales/client.en.yml

@@ -1950,6 +1950,8 @@ en:
       watching_first_post: "<span>New Topic</span> %{description}"
       membership_request_accepted: "Membership accepted in '%{group_name}'"
       membership_request_consolidated: "%{count} open membership requests for '%{group_name}'"
+      reaction: "<span>%{username}</span> %{description}"
+      reaction_2: "<span>%{username}, %{username2}</span> %{description}"
 
       group_message_summary:
         one: "%{count} message in your %{group_name} inbox"
@@ -1991,6 +1993,7 @@ en:
         liked_consolidated: "new likes"
         post_approved: "post approved"
         membership_request_consolidated: "new membership requests"
+        reaction: "new reaction"
 
     upload_selector:
       title: "Add an image"