Add binding for saving tmux buffer

Signed-off-by: Matej Focko <me@mfocko.xyz>

playbooks/roles/shell/templates/tmux.conf.j2

@@ -24,6 +24,7 @@ bind - resize-pane -D 2
 bind-key r clear-history
 bind-key R source-file ~/.tmux.conf \; display "Reloaded config file ~/.tmux.conf"
 bind-key b set status
+bind-key P command-prompt -p 'save history to filename:' -I '~/tmux.history' 'capture-pane -S - ; save-buffer %1 ; delete-buffer'
 
 source-file ~/.tmux/status.conf
 set -g status-position bottom