Fix [flags] appearing at end of usage

Turns out Cobra searches your usage line for the specific text "[flags]"
and if it doesn't find it, shoves it on the end. Gross. For that reason,
let's remove explicit callout of any flags and move it back to *before*
the double-hyphen.

cmd/foreach/foreach.go

@@ -47,7 +47,7 @@ func formatArguments(arguments []string) string {
 
 func NewForeachCmd() *cobra.Command {
 	cmd := &cobra.Command{
-		Use:   "foreach [--repos REPOFILE] -- COMMAND [ARGUMENT...]",
+		Use:   "foreach [flags] -- COMMAND [ARGUMENT...]",
 		Short: "Run COMMAND against each working copy",
 		Long:
 `Run COMMAND against each working copy. Make sure to include a

cmd/foreach/foreach_test.go

@@ -131,7 +131,7 @@ func TestHelpFlagReturnsUsage(t *testing.T) {
 	assert.NoError(t, err)
 	// should return usage
 	assert.Contains(t, out, "Usage:")
-	assert.Contains(t, out, "foreach [--repos REPOFILE] -- COMMAND [ARGUMENT...]")
+	assert.Contains(t, out, "foreach [flags] -- COMMAND [ARGUMENT...]")
 	assert.Contains(t, out, "Flags:")
 	assert.Contains(t, out, "help for foreach")