Update `English` translation

Currently translated at 100.0% (532 of 532 strings)

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

i18n/en.json

@@ -415,6 +415,7 @@
         "official": "Official wiki:",
         "pages": "Total pages:",
         "posts": "Discussion posts:",
+        "readonly": "This wiki is currently in read-only mode!",
         "rtl": "Right-to-left:",
         "talk": "talk",
         "topic": "Topic:",