Fix 301 error (trailing slashes)

README.md

 * [Nomad PHP Lightning Talks](https://www.youtube.com/c/nomadphp) - 10 to 15 minute Lightning Talks by PHP community members.
 * [PHP UK Conference](https://www.youtube.com/user/phpukconference/videos) - A collection of videos from the PHP UK Conference.
 * [Programming with Anthony](https://www.youtube.com/playlist?list=PLM-218uGSX3DQ3KsB5NJnuOqPqc5CW2kW) - A video series by Anthony Ferrara.
-* [Taking PHP Seriously](https://www.infoq.com/presentations/php-history) - A talk outlining PHP's strengths by Keith Adams of Facebook.
+* [Taking PHP Seriously](https://www.infoq.com/presentations/php-history/) - A talk outlining PHP's strengths by Keith Adams of Facebook.
 
 ### PHP Podcasts
 *Podcasts with a focus on PHP topics.*