Update free-podcasts-screencasts-en.md (#2555)

* Update free-podcasts-screencasts-en.md

added 2 new Podcasts.

* Remove trailing slash in URL

free-podcasts-screencasts-en.md

@@ -123,6 +123,7 @@
 * [Podcast] - [Frontend Five](https://frontendfive.codeschool.com)
 * [Podcast] - [JavaScript Air](https://javascriptair.com)
 * [Podcast] - [JavaScript Jabber](https://devchat.tv/js-jabber)
+* [Podcast] - [Syntax](https://syntax.fm)
 * [Podcast] - [The Javascript Show](http://javascriptshow.com)
 * [Screencast] - [Free Quality Javascript video tutorials and screencasts](http://www.screencasts.org/topics/javascript)
 * [Screencast] - [Node Tuts - Node.JS Video Tutorials](http://nodetuts.com)
@@ -176,6 +177,7 @@
 * [Podcast] - [The Silver Bullet Security Podcast with Gary McGraw](http://www.computer.org/web/computingnow/silverbullet)
 * [Podcast] - [The Web Ahead](http://5by5.tv/webahead)
 * [Podcast] - [The Web Platform](http://thewebplatform.libsyn.com)
+* [Podcast] - [This Developer's Life](http://thisdeveloperslife.com)
 * [Podcast] - [ThoughtWorks](https://soundcloud.com/thoughtworks)
 * [Podcast] - [Three Devs and a Maybe](http://threedevsandamaybe.com)
 * [Podcast] - [Toolsday](http://toolsday.io)