new book to add to the website

Dear www team,
the following us a patch to add a new book I've co-authored with
Enrico, hope it is fine for the addition on PostgreSQL web site.

Regards,
Luca

modified templates/pages/docs/books.html
@@ -10,7 +10,23 @@
<th>Information</th>
</tr>
</thead>
- <tbody>
+ <tbody>
+ <tr>
+ <td>
+ <a
href="https://www.packtpub.com/product/learn-postgresql-12/9781838985288">
+ <img
src="https://static.packt-cdn.com/products/9781838985288/cover/smaller"
+ alt="Learn PostgreSQL" />
+ </a>
+ </td>
+ <td>
+ <strong>Title</strong>: Learn PostgreSQL<br/>
+ <strong>Authors</strong>: Luca Ferrari, Enrico Pirozzi)<br/>
+ <strong>Language</strong>: English<br/>
+ <strong>Current version at publication</strong>: 13<br/>
+ <strong>Format</strong>: Paperback, eBook<br/>
+ <strong>Published</strong>: October 2020
+ </td>
+ </tr>
<tr>
<td>
<a href="https://postgrespro.com/education/books/introbook"><img