update readme file

Outputs:

none

You can also use a credential file as shown in /test:

```

credentials = jsondecode(fileread('credentials.json'));

opts = struct("username", credentials.username, "password",  credentials.password ,"maxDuration", false);

```

where the json file is so created:

```

{

    "username":"ygagarin",

    "password":":YG_password"

}

```

When the user will succesfully login via the login class method `MatMust_login()` a auth.json file with the authorization tocken will be wrote on your workingdirectory root.  

### MatMust_logincheck

{

	"username":"ygagarin",

	"password":":YG_password"

}

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