56345-structured-logging.md: add proposed vet check

Change-Id: I43c0016ff967be1bdd94f6a43818b54d9bf9b818
Reviewed-on: https://go-review.googlesource.com/c/proposal/+/447157
Run-TryBot: Jonathan Amsterdam <jba@google.com>
TryBot-Bypass: Jonathan Amsterdam <jba@google.com>
Reviewed-by: Alan Donovan <adonovan@google.com>
diff --git a/design/56345-structured-logging.md b/design/56345-structured-logging.md
index 93f6e6f..024afc5 100644
--- a/design/56345-structured-logging.md
+++ b/design/56345-structured-logging.md
@@ -579,6 +579,10 @@
 Each of these methods has a corresponding top-level function that uses the
 default logger.
 
+We will provide a vet check for the methods that take a list of `any` arguments
+to catch problems with missing keys or values.
+
+
 ```
 func (l Logger) Log(level Level, msg string, args ...any)
     Log emits a log record with the current time and the given level and