added html, css & JS content (#2267)

content/roadmaps/100-frontend/content/101-html/readme.md

@@ -4,6 +4,7 @@ HTML stands for HyperText Markup Language. It is used on the frontend and gives
 
 <ResourceGroupTitle>Free Content</ResourceGroupTitle>
 <BadgeLink badgeText='Read' colorScheme='yellow' href='https://www.w3schools.com/html/html_intro.asp'>W3Schools: Learn HTML</BadgeLink>
+<BadgeLink badgeText='Read' colorScheme='yellow' href='https://htmlreference.io/'>htmlreference.io: All HTML elements at a glance</BadgeLink>
 <BadgeLink badgeText='Course' colorScheme='green' href='https://www.internetingishard.com/html-and-css/'>Web Development Basics</BadgeLink>
 <BadgeLink badgeText='Course' colorScheme='green' href='https://www.codecademy.com/learn/learn-html'>Codecademy - Learn HTML</BadgeLink>
 <BadgeLink badgeText='Course' colorScheme='green' href='https://github.com/denysdovhan/learnyouhtml'>Interactive HTML Course</BadgeLink>

content/roadmaps/100-frontend/content/102-css/readme.md

@@ -4,6 +4,7 @@ CSS or Cascading Style Sheets is the language used to style the frontend of any
 
 <ResourceGroupTitle>Free Content</ResourceGroupTitle>
 <BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.w3schools.com/css/'>W3Schools — Learn CSS</BadgeLink>
+<BadgeLink badgeText='Read' colorScheme='yellow' href='https://cssreference.io/'>cssreference.io: All CSS properties at a glance</BadgeLink>
 <BadgeLink colorScheme='yellow' badgeText='Read' href='https://web.dev/learn/css/'>Web.dev by Google — Learn CSS</BadgeLink>
 <BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.freecodecamp.org/learn/responsive-web-design/'>freeCodeCamp — Responsive Web Design</BadgeLink>
 <BadgeLink colorScheme='yellow' badgeText='Read' href='https://learn.shayhowe.com/html-css/building-your-first-web-page/'>Learn to Code HTML & CSS</BadgeLink>

content/roadmaps/100-frontend/content/103-javascript/readme.md

@@ -11,6 +11,7 @@ JavaScript allows you to add interactivity to your pages. Common examples that y
 <ResourceGroupTitle>Free Content</ResourceGroupTitle>
 <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://www.javascripttutorial.net/'>Learn JavaScript: Covered many topics</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>