Updating link

Would it be ok if we could update the link to Holidayextras please? We are moving over to .com and https :)

Author: Richard Stevens

Readme.md

@@ -147,7 +147,7 @@ spend more time on it (ordered by time of contribution):
   video encoding as a service, check it out)
 * [Joyent](http://www.joyent.com/)
 * [pinkbike.com](http://pinkbike.com/)
-* [Holiday Extras](http://www.holidayextras.co.uk/) (they are [hiring](http://join.holidayextras.co.uk/))
+* [Holiday Extras](https://www.holidayextras.com/) (they are [hiring](https://join.holidayextras.co.uk/))
 * [Newscope](http://newscope.com/) (they are [hiring](https://newscope.com/unternehmen/jobs/))
 
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