internal/scan: update show help message

The help message for the -show flag was incorrect. It now outputs the
correct supported values for -show.

Change-Id: Ib53562f5a663e56fe9972cba75b41b8bda87e1f3
Reviewed-on: https://go-review.googlesource.com/c/vuln/+/549315
Reviewed-by: Zvonimir Pavlinovic <zpavlinovic@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

Author: Maceo Thompson

cmd/govulncheck/testdata/testfiles/usage/usage.ct

@@ -20,7 +20,7 @@ Usage:
     	set the scanning level desired, one of module, package or symbol (default "symbol")
   -show list
     	enable display of additional information specified by the comma separated list
-    	The only supported value is 'traces'
+    	The supported values are 'traces','color', and 'version'
   -tags list
     	comma-separated list of build tags
   -test

internal/scan/flags.go

@@ -47,7 +47,7 @@ func parseFlags(cfg *config, stderr io.Writer, args []string) error {
 	flags.StringVar(&cfg.db, "db", "https://vuln.go.dev", "vulnerability database `url`")
 	flags.StringVar(&cfg.mode, "mode", modeSource, "supports source or binary")
 	flags.Var(&tagsFlag, "tags", "comma-separated `list` of build tags")
-	flags.Var(&showFlag, "show", "enable display of additional information specified by the comma separated `list`\nThe only supported value is 'traces'")
+	flags.Var(&showFlag, "show", "enable display of additional information specified by the comma separated `list`\nThe supported values are 'traces','color', and 'version'")
 	flags.BoolVar(&version, "version", false, "print the version information")
 	scanLevel := flags.String("scan", "symbol", "set the scanning level desired, one of module, package or symbol")
 	flags.Usage = func() {