Added MongoDB Bengali Course Tutorial (#7268)

* Update free-courses-bn.md

* using titles as it is

Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

courses/free-courses-bn.md

@@ -21,6 +21,7 @@
     * [Svelte](#svelte)
     * [Vue.js](#vuejs)
 * [Kotlin](#kotlin)
+* [MongoDB](#mongodb)
 * [MySQL](#mysql)
 * [PHP](#php)
 * [Programming paradigms](#programming-paradigms)
@@ -166,6 +167,11 @@
 * [Chapter 1 : Kotlin Basic Concepts Bangla](https://www.youtube.com/playlist?list=PL_XxuZqN0xVDpRWRnXPWZcWIvz0JbeQe5) - Stack Learner
 
 
+### MongoDB
+
+* [Mastering MongoDB](https://www.youtube.com/playlist?list=PLEYpvDF6qy8ZTUjMcg4WOUYMxQZDpRnBt) - Foyzul Karim
+
+
 ### MySQL
 
 * [Bangla MySQL Database Tutorials](https://www.youtube.com/playlist?list=PLTydW-y9HsbQ2ztoaLBJTd4wwjc_oqWx4) - Delowar Jahan Imran, Training with Live Project (YouTube)