Merge pull request #242 from php-http/fix-message

better exception message when no php-http message factories are found

Author: dbu

src/MessageFactoryDiscovery.php

@@ -26,7 +26,7 @@ public static function find()
         try {
             $messageFactory = static::findOneByType(MessageFactory::class);
         } catch (DiscoveryFailedException $e) {
-            throw new NotFoundException('No message factories found. To use Guzzle, Diactoros or Slim Framework factories install php-http/message and the chosen message implementation.', 0, $e);
+            throw new NotFoundException('No php-http message factories found. Note that the php-http message factories are deprecated in favor of the PSR-17 message factories. To use the legacy Guzzle, Diactoros or Slim Framework factories of php-http, install php-http/message and php-http/message-factory and the chosen message implementation.', 0, $e);
         }
 
         return static::instantiateClass($messageFactory);