_content/doc/go1.24.md: update printf analyzer documentation

Update the documentation for the new printf analyzer check, now that it
only applies to 1.24 code.

Change-Id: I92e718c52a6faaec7fc74b7763de295184430935
Reviewed-on: https://go-review.googlesource.com/c/website/+/646235
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>

_content/doc/go1.24.md

@@ -116,7 +116,10 @@ The existing `printf` analyzer now reports a diagnostic for calls of
 the form `fmt.Printf(s)`, where `s` is a non-constant format string,
 with no other arguments. Such calls are nearly always a mistake
 as the value of `s` may contain the `%` symbol; use `fmt.Print` instead.
-See [#60529](/issue/60529).
+See [#60529](/issue/60529). This check tends to produce findings in existing
+code, and so is only applied when the language version (as specified by the
+go.mod `go` directive or `//go:build` comments) is at least Go 1.24, to avoid
+causing continuous integration failures when updating to the 1.24 Go toolchain.
 
 <!-- go.dev/issue/64127 -->
 The existing `buildtag` analyzer now reports a diagnostic when