docs: take the first person out of the checker's messages

mews/app.py

@@ -137,7 +137,7 @@ def _check(raw_url: str, client: str, listing: bool) -> bytes:
 
     if outcome.report is None:
         return pages.message(
-            "We couldn't check that page",
+            "That page couldn't be checked",
             [outcome.message or "Something went wrong. Try again."],
             [("/check", "Try again"), ("/spec/0.1", "The spec")],
         ).encode()