Add a year to”time of writing” reference

[yglik]

Hi,
I really enjoy the book, such an awesome idea to have a book to tell about the story of Wordpress.

In https://wordpress.org/book/2023/05/chapter-3-plugging-into-plugins/
Just below the headline: A Plugin Explosion
There is this sentence!
There are — at the time of writing — over 60,000 plugins.

And I really want to know what the year is, I guess some others would like it too.