[HttpClient] wrap class name in backticks, remove slashes from example code

Author: pizzaminded

http_client.rst

@@ -728,12 +728,12 @@ When using this component in a full-stack Symfony application, this behavior is
 not configurable and cURL will be used automatically if the cURL PHP extension
 is installed and enabled. Otherwise, the native PHP streams will be used.
 
-Providing additional options to CurlHttpClient
+Providing Additional Options to CurlHttpClient
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-It is possible to provide additional cURL options to CurlHttpClient. PHP exposes
+It is possible to provide additional cURL options to ``CurlHttpClient``. PHP exposes
 a lot of `cURL options`_ that can be passed to ``curl_setopt`` function, but only some
-of them are used in CurlHttpClient in favor of bigger component portability.
+of them are used in ``CurlHttpClient`` in favor of bigger component portability.
 
 To provide cURL-related parameters to request, add an ``extra.curl`` option in your
 configuration::
@@ -746,13 +746,13 @@ configuration::
         // ...
         'extra' => [
             'curl' => [
-                \CURLOPT_IPRESOLVE => \CURL_IPRESOLVE_V6
+                CURLOPT_IPRESOLVE => CURL_IPRESOLVE_V6
             ]
         ]
     ]);
 
 
-This option is available only when using CurlHttpClient, other clients will ignore these options.
+This option is available only when using ``CurlHttpClient``, other clients will ignore these options.
 
 .. note::