Sending a file by URL only works for certaining file types. If you want to upload other types of files you will have to post the file, after saving it on your own server, using multipart/form-data.
Sending by URL
In sendDocument, sending by URL will currently only
work for gif, pdf and zip files. [doc]
Sending file in PHP
$filepath = realpath('folder/.attheme');
$post = array('chat_id' => $GLOBALS["chat_id"],'document'=>new CurlFile($filepath));
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,"https://api.telegram.org/bot" . $GLOBALS["token"] . "/sendDocument");
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post);
curl_exec ($ch);
curl_close ($ch);