added extra information to prevent composer errors

gauravmokhasi · web-flow · commit a382848e7f1b · 2017-01-31T11:22:39.000+05:30
diff --git a/README.md b/README.md
@@ -12,11 +12,21 @@ The samples are all completely independent and self-contained so you can look at
 
 ##Running the Samples
 Clone this repository.  
-Run "composer update" in the root directory.  
+Run "composer update" in the root directory. 
 Run the individual samples e.g.   
 ````
 php PaymentTransactions/charge-credit-card.php
 ````
+Note: If during "composer update", you get the error "composer failed to open stream invalid argument", go to your php.ini file (present where you have installed PHP), and uncomment the following lines:
+````
+extension=php_openssl.dll
+extension=php_curl.dll
+````
+On Windows systems, you also have to uncomment:
+````
+extension_dir = "ext"
+````
+Then run the composer update again. You might have to restart your machine before the changes take effect.
 
 ##What if I'm not using Composer?
 We provide a custom `SPL` autoloader, just [download the SDK.](https://github.com/AuthorizeNet/sdk-php/releases):
