book: update nl

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

Author: ttaylorr

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

@@ -8,7 +8,7 @@
   language_code: nl
   front_page: true
   repository_url: https://github.com/progit/progit2-nl
-  sha: 2b996ba1615f6754e2dd944fd7508e442c849758
+  sha: 15dbf3f9732f6337ecc9e888da96bb0131566f6a
   ebook_pdf: https://github.com/progit/progit2-nl/releases/download/2.1.117/progit.pdf
   ebook_epub: https://github.com/progit/progit2-nl/releases/download/2.1.117/progit.epub
 page_title: Git - Book

external/book/sync/book-nl.sha

@@ -1 +1 @@
-2b996ba1615f6754e2dd944fd7508e442c849758
+15dbf3f9732f6337ecc9e888da96bb0131566f6a