.tmux.conf: Set window index to 1

I'm all for zero-based indexes, but this doesn't really make sense
on the keyboard as the numbers start at 1. :)

Great tip from https://mutelight.org/practical-tmux

.tmux.conf

@@ -82,6 +82,9 @@ set -s escape-time 0
 # use vi-style key bindings
 set-option -g mode-keys vi
 
+# start numbering windows a 1
+set -g base-index 1
+
 # Rather than constraining window size to the maximum size of any client
 # connected to the *session*, constrain window size to the maximum size
 # of any client connected to *that window*. Much more reasonable.