Added Content to Learn Astro (#10766)

* Added Content to Learn Astro

* Added Astro to Javascript

* Fixed Linter Error

* Update courses/free-courses-en.md

---------

Co-authored-by: Eric Hellman <eric@hellman.net>

courses/free-courses-en.md

@@ -51,6 +51,7 @@
 * [JavaScript](#javascript)
     * [Angular](#angular)
         * [AngularJS](#angularjs)
+    * [Astro](#astro)
     * [D3.js](#d3js)
     * [Deno](#deno)
     * [Electron](#electron)
@@ -1002,6 +1003,13 @@
 * [Shaping up with Angular.js](https://www.codeschool.com/courses/shaping-up-with-angular-js) - Codeschool (Codeschool account *required*)
 
 
+### Astro
+
+* [Astro Blog Course](https://www.youtube.com/playlist?list=PLoqZcxvpWzzeRwF8TEpXHtO7KYY6cNJeF) - Coding in Public
+* [Astro Crash Course](https://www.youtube.com/watch?v=Oi9z5gfIHJs) - Traversy Media
+* [Astro Web Framework Crash Course](https://www.youtube.com/watch?v=e-hTm5VmofI) - freeCodeCamp
+
+
 #### D3.js
 
 * [D3 101](https://www.youtube.com/playlist?list=PL9yYRbwpkykvjkfuRslECO9c1qTq3GgUb) - Curran Kelleher