readme setup cmd: added zathura

README.md

@@ -3,7 +3,7 @@
 ## setup
 
 ```sh
-sudo apt-get install latexmk
+sudo apt-get install latexmk zathura
 git clone git@git.hammerle.me:fphammerle/config-latexmk.git ~/.config/latexmk
 ln --symbolic --backup=numbered ~/.config/latexmk/latexmkrc ~/.latexmkrc
 ```