upgrade guzzle version and min php version

add usage example

README.md

@@ -1,5 +1,35 @@
 # php-ripple-lib
 PHP API for interacting with the XRP Ledger
 
+Upgrade guzzle to version 7.*
+
+Min php supported version 7.2
+
 ## Installation
 `composer require lessmore92/php-ripple-lib`
+
+
+## Sample Usage
+```php
+require_once "vendor/autoload.php";
+
+$options = [
+    'server'  => 'https://s.altnet.rippletest.net:51234',
+    'timeOut' => 5,
+];
+
+$api    = new \Lessmore92\Ripple\RippleAPI($options);
+$server = $api->serverInfo();
+var_dump($server);
+
+$address = 'rEdhDpVvmryJcMNcFTzXW3hAmiCkUXUru6';
+$balance = $api->accountInfo($address)->balance->toXrp();
+var_dump($balance);
+
+$txs = $api->accountTx($address, []);
+var_dump($txs);
+
+$fee = $api->getFee();
+var_dump($fee);
+
+```

composer.json

@@ -19,10 +19,10 @@
   ],
   "minimum-stability": "dev",
   "require": {
-    "php": ">7",
+    "php": ">7.2",
     "lessmore92/php-ripple-keypairs": "^v1.0",
     "lessmore92/php-ripple-binary-codec": "^v1.0",
-    "guzzlehttp/guzzle": "^6.3"
+    "guzzlehttp/guzzle": "7.*"
   },
   "autoload": {
     "psr-4": {