Correct Golden Ratio error in preface

mariadb_pdf/preface.html

@@ -62,7 +62,7 @@ <h3>This Book’s Structure</h3>
 
 <h3>This Book’s Format</h3>
 
-<p>There is currently just one version of the book. It’s delivered in the PDF format, and in the Golden Ratio aspect ratio – meaning, A4. As we envision it to be read mostly on-screen anyway, we wanted to avoid the additional complexity of also providing a US Letter format. If we meet demand for further versions, doing US Letter is of course an option; however, given there are many ways to improve the documentation, we would also like to understand how adding another aspect ratio of the PDF would benefit the users in practice.</p>
+<p>There is currently just one version of the book. It’s delivered in the PDF format, and in the 1 / sqrt(2) aspect ratio, meaning A4. As we envision it to be read mostly on-screen anyway, we wanted to avoid the additional complexity of also providing a US Letter format. If we meet demand for further versions, doing US Letter is of course an option; however, given there are many ways to improve the documentation, we would also like to understand how adding another aspect ratio of the PDF would benefit the users in practice.</p>
 
 <p>We don’t yet provide the ePub format. Again, if you desire ePub, please educate us as to what added benefits you expect of ePub on top of PDF.</p>
 
@@ -128,7 +128,7 @@ <h3>Acknowledgements</h3>
 
 <p>All in all, thank you to everyone who has contributed to this book! We hope compiling it into one volume is of use for you, and we would love to hear what you think about the end result.</p>
 
-<p>Munich, Germany, October 2022</p>
+<p>Munich, Germany, October 2022, updated October 2024</p>
 
 <p>Kaj Arnö, CEO, MariaDB Foundation</p>
-<div style = "page-break-after:always;"></div>
+<div style = "page-break-after:always;"></div>