add completion for zsh and .topography file to install script

completion/_auto.zsh

@@ -0,0 +1,23 @@
+#compdef auto.
+
+_arguments \
+	'1:flag:->flags' \
+	'*:: :->args'
+
+case "$state" in
+	flags)
+		local -a opts
+		opts=(
+		'-t:Topography file'
+		'-i:Install dotfiles specified in the .topography file'
+		'-u:Uninstall dotfiles specified in the .topography file'
+		'-b:Exit at first error'
+		'-h:Show help text'
+		)
+		_describe 'flags' opts
+		;;
+  args)
+		case $line[1] in
+			-t) _files ;;
+		esac
+esac