chore: Translate pressbooks-book.pot in ja

100% translated source file: 'pressbooks-book.pot'
on 'ja'.

Author: transifex-integration[bot]

languages/ja.po

@@ -228,7 +228,7 @@ msgstr "All Rights Reserved"
 
 #: inc/helpers/namespace.php:179
 msgid "Check out this great book published with Pressbooks."
-msgstr ""
+msgstr "Pressbooks から出版されたこの偉大なる本を表示"
 
 #: inc/helpers/namespace.php:252
 msgid "Home"