Update free-courses-bn.md (#6891)

* Update free-courses-bn.md

Added Mern stack bangla playlist

* Update free-courses-bn.md

courses/free-courses-bn.md

@@ -122,6 +122,7 @@
 
 #### Node.js
 
+* [Complete MERN Stack Course in Bangla](https://www.youtube.com/watch?v=ewBBT6Iph0M&list=PL_XxuZqN0xVD0op-QDEgyXFA4fRPChvkl) - Stack Learner
 * [Dive Into NodeJS](https://www.youtube.com/playlist?list=PL_XxuZqN0xVDHFj-ecFSU0SU-B0TuJRk9) - Stack Learner
 * [Node.js Tutorial Bangla  Series for Beginners](https://youtube.com/playlist?list=PLHiZ4m8vCp9PHnOIT7gd30PCBoYCpGoQM) - Learn With Sumit
 * [Raw Node JS Project in Bangla ( বাংলা ) - Uptime Monitoring API](https://youtube.com/playlist?list=PLHiZ4m8vCp9OmVWU2Qf9tZgKdyzoubOpj) - Learn With Sumit