Correct wrong instrumentation name (#165)

This is part of the Symfony auto-instrumentation

Author: xvilo

_register.php

@@ -11,7 +11,7 @@
 }
 
 if (extension_loaded('opentelemetry') === false) {
-    trigger_error('The opentelemetry extension must be loaded in order to autoload the OpenTelemetry Laravel auto-instrumentation', E_USER_WARNING);
+    trigger_error('The opentelemetry extension must be loaded in order to autoload the OpenTelemetry Symfony auto-instrumentation', E_USER_WARNING);
 
     return;
 }