Indicate where min-fresh requirement came from

JunTaoLuo · JunTaoLuo · commit 714104100aa6 · 2016-10-05T17:59:26.000-07:00
diff --git a/src/Microsoft.AspNetCore.ResponseCaching/Internal/LoggerExtensions.cs b/src/Microsoft.AspNetCore.ResponseCaching/Internal/LoggerExtensions.cs
@@ -62,7 +62,7 @@ static LoggerExtensions()
             _logExpirationMinFreshAdded = LoggerMessage.Define<TimeSpan>(
                 logLevel: LogLevel.Debug,
                 eventId: 5,
-                formatString: "Adding a minimum freshness requirement of {Duration}.");
+                formatString: "Adding a minimum freshness requirement of {Duration} specified by the 'min-fresh' cache directive.");
             _logExpirationSharedMaxAgeExceeded = LoggerMessage.Define<TimeSpan, TimeSpan>(
                 logLevel: LogLevel.Debug,
                 eventId: 6,
