Add JetBrains sponsorship to README with H1 heading (#376)

Author: g105b

README.md

@@ -83,3 +83,9 @@ $userName = $db->fetchString("user/getUsernameById", 105);
 [wiki-migrations]: https://www.php.gt/docs/database/migrations
 [wiki-config]: https://www.php.gt/docs/database/config
 [wiki-type-safety]: https://www.php.gt/docs/database/type-safety
+
+# Proudly sponsored by
+
+[JetBrains Open Source sponsorship program](https://www.jetbrains.com/community/opensource/)
+
+[![JetBrains logo.](https://resources.jetbrains.com/storage/products/company/brand/logos/jetbrains.svg)](https://www.jetbrains.com/community/opensource/)