Update README.md

Use facebook/graph-sdk

Author: venca-x

README.md

@@ -18,7 +18,7 @@ Installation
 
 Add the bundle to your dependencies:
 ```
-composer require facebook/php-sdk-v4:5.0.*
+composer require facebook/graph-sdk:~5.4
 composer require google/apiclient:~2.0
 composer require kertz/twitteroauth:dev-master
 composer require venca-x/social-login:~1.0.0
@@ -31,7 +31,7 @@ Final composer.json:
    // ...
    "require": {
        // ...
-       "facebook/php-sdk-v4" : "5.0.*",
+       "facebook/graph-sdk" : "^5.4",
        "google/apiclient": "~2.0",
        "kertz/twitteroauth": "dev-master",
        "venca-x/social-login": "~1.0.0"