Remove Tmux primer link from tutorials section

link is 404ing

Author: rothgar

README.md

@@ -19,7 +19,6 @@ List of helpful tmux links for various tutorials, plugins, and configuration set
 
 - [Automatically start tmux on SSH](http://marklodato.github.io/2013/10/31/autostart-tmux-on-ssh.html)
 - [Tmux crash course](https://thoughtbot.com/blog/a-tmux-crash-course)
-- [Tmux primer](https://danielmiessler.com/study/tmux/)
 - [Tmux and Vim together](https://www.bugsnag.com/blog/tmux-and-vim)
 
 ## <a name="cheatsheets"></a>Cheat Sheets