fix the error of flag usage description on tcping command (#15)

Co-authored-by: lushan <[email protected]>

Author: lushan01

main.go

@@ -165,8 +165,8 @@ func init() {
 	rootCmd.Flags().StringVarP(&interval, "interval", "I", "1s", `ping interval, units are "ns", "us" (or "µs"), "ms", "s", "m", "h"`)
 
 	rootCmd.Flags().BoolVarP(&httpMode, "http", "H", false, `Use "HTTP" mode. will ignore URI Schema, force to http`)
-	rootCmd.Flags().BoolVar(&httpHead, "head", false, `Use POST instead of GET in http mode.`)
-	rootCmd.Flags().BoolVar(&httpPost, "post", false, `Use HEAD instead of GET in http mode.`)
+	rootCmd.Flags().BoolVar(&httpHead, "head", false, `Use HEAD instead of GET in http mode.`)
+	rootCmd.Flags().BoolVar(&httpPost, "post", false, `Use POST instead of GET in http mode.`)
 	rootCmd.Flags().StringVar(&httpUA, "user-agent", "tcping", `Use custom UA in http mode.`)
 
 	rootCmd.Flags().StringArrayVarP(&dnsServer, "dns-server", "D", nil, `Use the specified dns resolve server.`)