fix typo

Author: phulstaert

frontend/js/i18n/messages.json

@@ -205,7 +205,7 @@
       "reachability-wrong-data": "There is a server found at this ___domain but it returned an unexpected data. Is it the NPM server? Please make sure your ___domain points to the IP where your NPM instance is running.",
       "reachability-other": "There is a server found at this ___domain but it returned an unexpected status code {code}. Is it the NPM server? Please make sure your ___domain points to the IP where your NPM instance is running.",
       "download": "Download",
-      "renew-title": "Renew Let'sEncrypt Certificate",
+      "renew-title": "Renew Let's Encrypt Certificate",
       "search": "Search Certificate…"
     },
     "access-lists": {