Added new course for blockchain (#8910)

courses/free-courses-hi.md

@@ -112,6 +112,7 @@
 
 * [Blockchain Full Course in Hindi](https://www.youtube.com/playlist?list=PLgPmWS2dQHW-BRQCQCNYgmHUfCN115pn0) - Code Eater (YouTube)
 * [Blockchain Full Course in Hindi](https://www.youtube.com/playlist?list=PLRlT7xBRpp9MiMN25XJjUVz01rGFQohq2) - Innovate India
+* [Complete Blockchain Development Course for Beginners in Hindi](https://www.youtube.com/watch?v=RkYVVC2vXho) - web3Mantra
 * [Solidity ^0.8 | Blockchain | In Hindi](https://www.youtube.com/playlist?list=PL-Jc9J83PIiG6_thChXWzolj9BEG-Y0gh) - Pepcoding (YouTube)