Update README.md

Author: yurikuzn

README.md

@@ -1 +1,43 @@
 # PHP EspoCRM API client
+
+Require with Composer:
+
+```
+composer require espocrm/php-espo-api-client
+```
+
+Usage:
+
+```
+use Espo\ApiClient\Client;
+use Espo\ApiClient\Header;
+use Espo\ApiClient\Exception\ResponseError;
+
+$client = new Client($yourEspoUrl);
+$client->setApiKey($apiKey);
+$client->setSecretKey($secretKey); // if you use HMAC method
+
+try {
+    $response = $client->request(
+        Client::METHOD_POST,
+        'Lead',
+        [
+            'firstName' => $firstName,
+            'lastName' => $lastName,
+            'emailAddress' => $emailAddress,
+        ],
+        [
+            new Header('X-Skip-Duplicate-Check', 'true')   
+        ]
+    );
+    
+    $parsedBody = $response->getParsedBody();
+}
+catch (ResponseError $e) {
+    // Error response.
+    $response = $e->getResponse();    
+    
+    $code = $response->getCode();
+    $body = $response->getBody();
+}
+```