Add locale

app/soapbox/locales/en.json

@@ -528,6 +528,7 @@
   "confirmations.scheduled_status_delete.heading": "Cancel scheduled post",
   "confirmations.scheduled_status_delete.message": "Are you sure you want to cancel this scheduled post?",
   "confirmations.unfollow.confirm": "Unfollow",
+  "copy.success": "Copied to clipboard!",
   "crypto_donate.explanation_box.message": "{siteTitle} accepts cryptocurrency donations. You may send a donation to any of the addresses below. Thank you for your support!",
   "crypto_donate.explanation_box.title": "Sending cryptocurrency donations",
   "crypto_donate_panel.actions.view": "Click to see {count, plural, one {# wallet} other {# wallets}}",