Feature: Add Backend Essentials Section with Workshops (#11731)

* Add: Assembly Language Course

* Add: C++ STL & Electron.js Course

* Fix: Linter Error

* Update free-courses-bn.md

* Update free-courses-bn.md

* Update free-courses-bn.md

* Update free-courses-bn.md

* Fix: URL Updates

* Add: Backend Essentials Topic

* Fix: Writing Changes

courses/free-courses-bn.md

@@ -38,6 +38,7 @@
     * [Flask](#flask)
 * [Scratch](#scratch)
 * [Shell scripting](#shell-scripting)
+* [Software Architecture](#software-architecture)
 * [Swift](#swift)
 * [TypeScript](#typescript)
 * [WordPress](#wordpress)
@@ -352,6 +353,15 @@
 * [Shell Scripting Tutorial in Bangla](https://www.youtube.com/playlist?list=PLuDISCShhAlxIduQrBqee-dlCAQTygm4l) - Mohammad Shakirul Islam
 
 
+### Software Architecture
+
+* [Career in Backend Workshop](https://www.youtube.com/playlist?list=PL_XxuZqN0xVB2m_jJ1QYOFD2D4JZuY6fO) - Stack Learner
+* [Practical Microservices Workshop](https://www.youtube.com/playlist?list=PL_XxuZqN0xVAO0uVm0ClJ3wsKHJw6G_TL) - Stack Learner
+* [Pro Postman Workshop](https://www.youtube.com/playlist?list=PL_XxuZqN0xVAw_wmOs1iVfdFGiAX-wGKF) - Stack Learner
+* [REST API Design Workshop](https://www.youtube.com/playlist?list=PL_XxuZqN0xVAWGDKIzcn6NWikVkljJQZc) - Stack Learner
+* [System Design & Application Architecture Workshop](https://www.youtube.com/playlist?list=PL_XxuZqN0xVAiu5oODf-SmeXG2Y_RG2pz) - Stack Learner
+
+
 ### Swift
 
 * [Swift Programming Tutorial](https://www.youtube.com/playlist?list=PLO3_9DDlL5oQtl1_DmfAC6lAC2IoHx31K) - FHT Bangla