Add what is JavaScript content (#1545)

* JavaScript description 

basic JavaScript description on "What is javascript ?" page.

* Update content/roadmaps/106-javascript/content/100-javascript-introduction/100-what-is-javascript.md

Co-authored-by: Kamran Ahmed <kamranahmed.se@gmail.com>

content/roadmaps/106-javascript/content/100-javascript-introduction/100-what-is-javascript.md

@@ -1 +1,12 @@
-# What is javascript
+# What is JavaScript?
+
+JavaScript, often abbreviated JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. It lets us add interactivity to pages e.g. you might have seen sliders, alerts, click interactions, popups, etc on different websites -- all of that is built using JavaScript. Apart from being used in the browser, it is also used in other non-browser environments as well such as Node.js for writing server-side code in JavaScript, Electron for writing desktop applications, React Native for mobile applications, and so on. 
+
+<ResourceGroupTitle>Free Content</ResourceGroupTitle>
+<BadgeLink colorScheme='Read' badgeText='yellow' href='https://developer.mozilla.org/en-US/docs/Web/JavaScript'>JavaScript MDN Docs</BadgeLink>=
+<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='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>
+