Use consistent first uppercase char in MD_STD reference to exception

src/MD_STD.php

@@ -301,7 +301,7 @@ public static function runCurl(string $url, int $timeout = 1200):string {
     public static function runCurlMulti(array $urls, int $timeout = 1200):array {
 
         if (!($mh = curl_multi_init())) {
-            throw new exception("Failed to set up multi handle");
+            throw new Exception("Failed to set up multi handle");
         }
 
         $curl_array = [];