Remove duplicate option append_history

The option inc_append_history already has the same effect.

lib/history.zsh

@@ -32,7 +32,6 @@ HISTSIZE=10000
 SAVEHIST=10000
 
 ## History command configuration
-setopt append_history         # append history to HISTFILE on session exit
 setopt extended_history       # record timestamp of command in HISTFILE
 setopt hist_expire_dups_first # delete duplicates first when HISTFILE size exceeds HISTSIZE
 setopt hist_ignore_dups       # ignore duplicated commands history list