Say what happens instead of making files do things

A file is written to; it does not write, score or name anything. Five comments
and doc lines said otherwise, two of them older than today.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RoGtneMQaz4M9w7Kk49AVD

tests/Nonemm.Contests.Tests/UdcScoringTests.cs

@@ -275,8 +275,8 @@ public class UdcScoringTests
         Assert.Single(LogFor(contest).Judge(TestLog.Contact("OM3XYZ", section: "NOV")).NewMultipliers);
     }
 
-    /// `Country` is what a published file writes where the editor writes
-    /// `CountryPrefix`.
+    /// Published files hold `Country` in this key; the UDC editor puts
+    /// `CountryPrefix` there.
     [Fact]
     public void CountryIsTheSameSourceAsCountryPrefix() =>
         Assert.Equal(