Update free-courses-en.md (#8217)

* Update free-courses-en.md

* Added categories in cloud computing

* fix linking

courses/free-courses-en.md

@@ -14,6 +14,9 @@
 * [C++](#cpp)
 * [Clojure](#clojure)
 * [Cloud Computing](#cloud-computing)
+    * [AWS](#aws)
+    * [Azure](#azure)
+    * [IBM](#ibm)
 * [Compilers](#compilers)
 * [Computer Organization and Architecture](#computer-organization-and-architecture)
 * [Computer Science](#computer-science)
@@ -296,11 +299,24 @@
 
 * [Cloud Computing and Development](https://uaceit.com/courses/cloud-computing-and-development) - Ashwin Kumar Ramaswamy (UAceIt) (email address *required*)
 * [Cloud Computing Full Course In 11 Hours \| Cloud Computing Tutorial For Beginners](https://www.youtube.com/watch?v=2LaAJq1lB1Q) - Edureka!
-* [IBM Cloud Essentials V3](https://cognitiveclass.ai/courses/ibm-cloud-essentials) - CognitiveClass.ai
 * [Introduction to Cloud](https://cognitiveclass.ai/courses/introduction-to-cloud) - CognitiveClass.ai
+
+
+#### AWS
+
+* [Cloud Computing Basics with AWS](https://trailhead.salesforce.com/content/learn/modules/aws-cloud) - Trailhead (Salesforce) (email address *required*)
+
+
+#### Azure
+
 * [Microsoft Certified: Azure Fundamentals](https://docs.microsoft.com/en-us/learn/certifications/azure-fundamentals/) - Microsoft
 
 
+#### IBM
+
+* [IBM Cloud Essentials V3](https://cognitiveclass.ai/courses/ibm-cloud-essentials) - CognitiveClass.ai
+
+
 ### Compilers
 
 * [Compiler Design](https://www.youtube.com/playlist?list=PLLvKknWU7N4zpJWLqk7DXK26JwTB-gFmZ) - Lalit Vashistha