docs: update link in thanks

man/fragments/_thanks.Rmd

 
 **xaringanthemer** was built by [Garrick Aden-Buie](https://www.garrickadenbuie.com) ([@grrrck](https://twitter.com/grrrck)).
 
-Big thank you to [Yihui Xie](https://yihui.org), especially for [xaringan].
-Also thanks to [Ole Petter Bang](http://www.gnab.org/) for [remark.js][remarkjs].
+Big thank you to [Yihui Xie](https://yihui.org/), especially for [xaringan].
+Also thanks to [Ole Petter Bang](https://gnab.org/) for [remark.js][remarkjs].
 
-Feel free to [file an issue](https://github.com/gadenbuie/xaringanthemer/issues) 
+Feel free to [file an issue](https://github.com/gadenbuie/xaringanthemer/issues)
 if you find a bug or have a theme suggestion -- or better yet, submit a pull request!