Update `English` translation

Currently translated at 100.0% (528 of 528 strings)

Translation: Wiki-Bot/Discord
Translate-URL: https://weblate.frisk.space/projects/wiki-bot/discord/en/

i18n/en.json

@@ -415,6 +415,7 @@
         "posts": "Discussion posts:",
         "talk": "talk",
         "topic": "Topic:",
+        "unknown": "*unknown*",
         "users": "Active users:",
         "version": "Version:",
         "vertical": "Vertical:",