book: update uk

Updated via the `update-book.yml` GitHub workflow.

Author: dscho

external/book/content/book/uk/v1/_index.html

@@ -0,0 +1,4 @@
+---
+### DO NOT EDIT! Generated by script/update-book2.rb
+redirect_to: book/uk/v2
+---

external/book/content/book/uk/v2/_index.html

@@ -13,5 +13,6 @@
 url: "/book/uk/v2.html"
 aliases:
 - "/book/uk/v2/index.html"
+- "/book/uk/v1/index.html"
 - "/book/uk/index.html"
 ---