book: update en

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

Author: ttaylorr

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

@@ -8,10 +8,10 @@
   language_code: en
   front_page: true
   repository_url: https://github.com/progit/progit2
-  sha: 181ebf9cd07b0338cf659fd64267dcf6fd74dbc4
-  ebook_pdf: https://github.com/progit/progit2/releases/download/2.1.438/progit.pdf
-  ebook_epub: https://github.com/progit/progit2/releases/download/2.1.438/progit.epub
-  ebook_mobi: https://github.com/progit/progit2/releases/download/2.1.438/progit.mobi
+  sha: 051ae88b8c5d95298b39dc1d40a2c2b55c09b04c
+  ebook_pdf: https://github.com/progit/progit2/releases/download/2.1.439/progit.pdf
+  ebook_epub: https://github.com/progit/progit2/releases/download/2.1.439/progit.epub
+  ebook_mobi: https://github.com/progit/progit2/releases/download/2.1.439/progit.mobi
 page_title: Git - Book
 url: "/book/en/v2.html"
 aliases:

external/book/sync/book-en.sha

@@ -1 +1 @@
-181ebf9cd07b0338cf659fd64267dcf6fd74dbc4
+051ae88b8c5d95298b39dc1d40a2c2b55c09b04c