Add "Modern Fortran Tutorial"

Modern Fortran Tutorial
By: Yutaka Masuda @masuday

https://masuday.github.io/fortran_tutorial/

Part of: EbookFoundation/free-programming#5492

books/free-programming-books.md

@@ -1463,6 +1463,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [Fortran Wiki - Tutorials](http://fortranwiki.org/fortran/show/Tutorials) (HTML)
 * [Introduction to Fortran](https://qc2-teaching.readthedocs.io/en/latest/programming.html) - Sebastian Ehlert, Julius Stückrath, Marcel Mueller, Marcel Stahn (HTML)
 * [Modern Fortran in Science and Technology](https://modern-fortran-in-science-and-technology.readthedocs.io/en/latest) - Jonas Lindemann and Ola Dahlblom (HTML, [PDF](https://modern-fortran-in-science-and-technology.readthedocs.io/_/downloads/en/latest/pdf/), [EPUB](https://modern-fortran-in-science-and-technology.readthedocs.io/_/downloads/en/latest/epub/))
+* [Modern Fortran Tutorial](https://masuday.github.io/fortran_tutorial/) - Yutaka Masuda (HTML)
 * [Professional Programmer’s Guide to Fortran77 (2005)](https://www.star.le.ac.uk/~cgp/prof77.pdf) - Clive G. Page (PDF)
 * [Self Study Guide 2: Programming in Fortran 95](http://www.mrao.cam.ac.uk/~rachael/compphys/SelfStudyF95.pdf) - Dr Rachael Padman (PDF)