Update GUIDE.md

Author: Antonio Buedo

GUIDE.md

@@ -93,13 +93,7 @@ php composer.phar require bitpay/sdk-light:^2.0
 
 ### Initializing your BitPay light client
 
-Once you have the environment file (JSON or YML previously generated) you can initialize the client on two different ways:
-
-```php
-// Provide the full path to the env file which you have previously stored securely.
-
-$bitpay = BitPaySDKLight\Client::create()->withFile([FULL_PATH_TO_THE_CONFIG_FILE]);
-```
+Once you have your previously generated Token, you can initialize the client following this example:
 
 ```php
 $bitpay = new BitPaySDKLight\Client("CFJCZH3VitcEER9Uybx8LMvkPsSWzpSWvN4vhNEJp47b", BitPaySDKLight\Env::Test);
@@ -864,4 +858,4 @@ Body
 
 # Copyright
 
-Copyright (c) 2019 BitPay
+Copyright (c) 2019 BitPay