fix mixed content

Since the images are loaded on docker hub without going through a proxy like Github does the images were being loaded over http causing mixed content.

README.md

@@ -1,4 +1,4 @@
-![http://linuxserver.io](http://www.linuxserver.io/wp-content/uploads/2015/06/linuxserver_medium.png)
+![https://linuxserver.io](https://www.linuxserver.io/wp-content/uploads/2015/06/linuxserver_medium.png)
 
 The [LinuxServer.io](https://www.linuxserver.io/) team brings you another quality container release featuring auto-update on startup, easy user mapping and community support. Be sure to checkout our [forums](https://forum.linuxserver.io/index.php) or for real-time support our [IRC](https://www.linuxserver.io/index.php/irc/) on freenode at `#linuxserver.io`.