Update free-programming-books-langs.md (#6441)

* Update free-programming-books-langs.md

Added "How To Build Websites with HTML" by Erin Glass (DigitalOcean) and "Python Machine Learning Projects" by Lisa Tagliaferri and Brian Boucheron (DigitalOcean)

* Update books/free-programming-books-langs.md

Co-authored-by: CleanMachine1 <78213164+CleanMachine1@users.noreply.github.com>

* Update books/free-programming-books-langs.md

Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

* Update books/free-programming-books-langs.md

Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

Co-authored-by: CleanMachine1 <78213164+CleanMachine1@users.noreply.github.com>
Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

books/free-programming-books-langs.md

@@ -917,6 +917,7 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 * [DOM Enlightenment](http://domenlightenment.com) - Cody Lindley (HTML)
 * [GA Dash](https://dash.generalassemb.ly)
 * [Google's HTML/CSS Style Guide](https://google.github.io/styleguide/htmlcssguide.html)
+* [How To Build a Website with HTML](https://www.digitalocean.com/community/books/how-to-build-a-website-with-html-ebook) - Erin Glass (PDF, EPUB)
 * [How to Code in HTML5 and CSS3](https://web.archive.org/web/20180816174417/http://howtocodeinhtml.com/HowToCodeInHTML5AndCSS3.pdf) - Damian Wielgosik (PDF)
 * [HTML Canvas Deep Dive](http://joshondesign.com/p/books/canvasdeepdive/toc.html) - Josh Marinacci
 * [HTML Dog Tutorials](http://www.htmldog.com)