imagefilledpolygon example uses deprecated parameter

[ChrisHSandN]

From manual page: https://php.net/function.imagefilledpolygon
Edit: & https://www.php.net/manual/en/function.imageopenpolygon.php & https://www.php.net/manual/en/function.imagepolygon.php

The example is using the num_points parameter (which was deprecated in PHP 8.1)

Also the Run Code button on the GD pages results in:

Fatal error: Uncaught Error: Call to undefined function imagecreatetruecolor() in php-wasm run script:13
Stack trace:
#0 {main}
thrown in php-wasm run script on line 13

[sy-records]

Thanks for your feedback, I fixed the example error in #4388.

Fatal error: Uncaught Error: Call to undefined function imagecreatetruecolor() in php-wasm

it's done through WASM which is limited in what it can do, PHP-on-WASM is even more limited in what it supports. see #4353