Add undercurl to tmux

tmux/tmux.conf.symlink

@@ -1,6 +1,7 @@
 set -g default-command "zsh"
 set -g default-terminal "tmux-256color"
 set -g history-limit 20000
+set -as terminal-overrides ',*:Smulx=\E[4::%p1%dm'
 
 # automatically renumber tmux windows
 set -g renumber-windows on