Add new resource for Graph Theory course (#12933)

* Add new resource for Graph Theory course

* Update courses/free-courses-en.md

Co-authored-by: Eric Hellman <[email protected]>

* updated entry for Graph Theory

* Fix formatting of Graph Theory course entry

---------

Co-authored-by: Eric Hellman <[email protected]>

Author: Muditapandey26

courses/free-courses-en.md

@@ -881,6 +881,7 @@
 * [Graph Theory](https://www.youtube.com/playlist?list=PLztBpqftvzxXBhbYxoaZJmnZF6AUQr1mH) - Wrath of Math
 * [Graph Theory](https://nptel.ac.in/courses/111106102) - Prof. Soumen Maity (NPTEL)
 * [Graph Theory - DM](https://www.youtube.com/playlist?list=PLYrahs7hsYIQiSNxTfZndQz7jWPXsA1ur) - SCCI Labs IIT Ropar
+* [Graph Theory part-1](https://www.youtube.com/playlist?list=PLGxuz-nmYlQOiIOriTXMEoGoybUC3Jmrn) - Sarada Herke
 * [Graph Theory Playlist](https://www.youtube.com/playlist?list=PLDV1Zeh2NRsDGO4--qE8yH72HFL1Km93P) - WilliamFiset