Add Eloquent JavaScript book to JS roadmap (#1632)

Recommended because it's a very thorough and excellently written free, full-length textbook on JS. It's one of the resources that I most frequently saw mentioned when I was looking up how to learn JS, and it's the one that has helped me the most.

content/roadmaps/106-javascript/content/100-javascript-introduction/readme.md

@@ -7,5 +7,6 @@ JavaScript, often abbreviated JS, is a programming language that is one of the c
 <BadgeLink badgeText='Read' colorScheme="yellow" href='https://www.w3schools.com/js/'>W3Schools – JavaScript Tutorial</BadgeLink>
 <BadgeLink badgeText='Read' colorScheme="yellow" href='https://javascript.info/'>The Modern JavaScript Tutorial</BadgeLink>
 <BadgeLink badgeText='Read' colorScheme="yellow" href='https://exploringjs.com/'>Exploring JS: JavaScript books for programmers</BadgeLink>
+<BadgeLink badgeText='Read' colorScheme="yellow" href='https://eloquentjavascript.net/'>Eloquent JavaScript textbook</BadgeLink>
 <BadgeLink badgeText='Watch' href='https://youtu.be/hdI2bqOjy3c?t=2'>JavaScript Crash Course for Beginners</BadgeLink>
 <BadgeLink badgeText='Watch' href='https://youtu.be/P7t13SGytRk?t=22'>Build a Netflix Landing Page Clone with HTML, CSS & JS</BadgeLink>