Organize history.zsh file and improve comments

lib/history.zsh

-## Command history configuration
-[ -z "$HISTFILE" ] && HISTFILE="$HOME/.zsh_history"
-HISTSIZE=10000
-SAVEHIST=10000
-
 ## History wrapper
 function omz_history {
   # Delete the history file if `-c' argument provided.
@@ -23,11 +18,17 @@ case $HIST_STAMPS in
   *) alias history='omz_history' ;;
 esac
 
-setopt append_history
-setopt extended_history
-setopt hist_expire_dups_first
-setopt hist_ignore_dups # ignore duplication command history list
-setopt hist_ignore_space
-setopt hist_verify
-setopt inc_append_history
-setopt share_history # share command history data
+## History file configuration
+[ -z "$HISTFILE" ] && HISTFILE="$HOME/.zsh_history"
+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
+setopt hist_ignore_space      # ignore commands that start with space
+setopt hist_verify            # show command with history expansion to user before running it
+setopt inc_append_history     # add commands to HISTFILE in order of execution
+setopt share_history          # share command history data