cmd/upspin-audit: change default datadir to $HOME/upspin/audit

This is more discoverable and less ambiguous than 'store', which could
mean a lot of things in the context of Upspin.

Change-Id: I8f1324101d2af080a46f37fc74f7df3fc64e8690
Reviewed-on: https://upspin-review.googlesource.com/17420
Reviewed-by: Rob Pike <r@golang.org>
diff --git a/cmd/upspin-audit/main.go b/cmd/upspin-audit/main.go
index 9e498cc..284e439 100644
--- a/cmd/upspin-audit/main.go
+++ b/cmd/upspin-audit/main.go
@@ -86,7 +86,7 @@
 // Done here so the definition can be common among the commands.
 func dataDirFlag(fs *flag.FlagSet) *string {
 	var dataDir string
-	fs.StringVar(&dataDir, "data", filepath.Join(os.Getenv("HOME"), "upspin", "store"), "`directory` storing scan data")
+	fs.StringVar(&dataDir, "data", filepath.Join(os.Getenv("HOME"), "upspin", "audit"), "`directory` storing scan data")
 	return &dataDir
 }