add TimeFormat to README

Author: alehechka

README.md

@@ -37,6 +37,7 @@ json2go generate --url="https://gorest.co.in/public/v2/users"
 | Root Object Name | `--root=RootObject`          | `string` | Name for top-level object in JSON payload                                                                                                                                                          | `Root`     |
 | Package Name     | `--package=api`              | `string` | Name of package to generate types into. A nested package path is valid                                                                                                                             | `main`     |
 | Output File Name | `--output`                   | `string` | The name of the file that is generated. If a file is provided as input, will use matching name unless explicitly provided. The ".go" extension is not required and will be automatically appended. | `types.go` |
+| Time Format      | `--time=2006-01-02`          | `string` | Time format to use while parsing strings for potential time.Time variables. View time.Time constants for possible defaults: https://pkg.go.dev/time#pkg-constants                                  | `RFC3339`  |
 | Debug logging    | `--debug`                    | `bool`   | Will output debugging console logs.                                                                                                                                                                | `false`    |
 | Quiet            | `--quiet`                    | `bool`   | Will quiet fatal errors.                                                                                                                                                                           | `false`    |
 | STDOUT           | `--out`                      | `bool`   | Instead of generating a Go file, will instead print the contents to STDOUT                                                                                                                         | `false`    |

cmd/generate.go

@@ -54,7 +54,7 @@ var generateFlags = []cli.Flag{
 	&cli.StringFlag{
 		Name:    timeFormatFlag,
 		Aliases: []string{"t"},
-		Usage:   "Time format to use while parsing strings for potential time.Time variables.",
+		Usage:   "Time format to use while parsing strings for potential time.Time variables. View time.Time constants for possible defaults: https://pkg.go.dev/time#pkg-constants",
 		Value:   time.RFC3339,
 	},
 	&cli.BoolFlag{