cmd/preprofile: correct -V flag

Change-Id: I9a0dc3a4b4c81f0f6942badcd4643a74c5046440
GitHub-Last-Rev: d1fa4e5
GitHub-Pull-Request: #66949
Reviewed-on: https://go-review.googlesource.com/c/go/+/580615
LUCI-TryBot-Result: Go LUCI <[email protected]>
Auto-Submit: Ian Lance Taylor <[email protected]>
Reviewed-by: qiu laidongfeng2 <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>
Reviewed-by: Veronica Silina <[email protected]>

Author: And-ZJ

src/cmd/preprofile/main.go

@@ -8,7 +8,7 @@
 //
 // Usage:
 //
-//	go tool preprofile [-v] [-o output] -i input
+//	go tool preprofile [-V] [-o output] -i input
 package main
 
 import (
@@ -23,7 +23,7 @@ import (
 )
 
 func usage() {
-	fmt.Fprintf(os.Stderr, "usage: go tool preprofile [-v] [-o output] -i input\n\n")
+	fmt.Fprintf(os.Stderr, "usage: go tool preprofile [-V] [-o output] -i input\n\n")
 	flag.PrintDefaults()
 	os.Exit(2)
 }