Update free-courses-hi.md (#7145)

* Update free-courses-hi.md

added resource for graph playlist

* Update free-courses-hi.md

added resource for graph playlist

* Update free-courses-hi.md

Made suggested changes

* Removing instructor chunk from creators. It's implicit in the resource title

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

courses/free-courses-hi.md

@@ -95,6 +95,7 @@
 * [Dynamic Programming Playlist](https://www.youtube.com/playlist?list=PL_z_8CaSLPWekqhdCPmFohncHwz8TY2Go) - Aditya Verma
 * [Dynamic Programming Workshop](https://www.youtube.com/playlist?list=PLqf9emQRQrnKA_EeveiXQj_uP25w8_5qL) - Vivek Gupta
 * [Functions and Arrays - Level 1](https://www.youtube.com/playlist?list=PL-Jc9J83PIiHOV7lm2uSw4ZiVsIRsGS6r) - Pepcoding
+* [Graph Series by Striver \| C++ \| Java \| Interview Centric \| Algorithms \| Problems](https://www.youtube.com/playlist?list=PLgUwDviBIf0oE3gA41TKO2H5bHpPd7fzn) - take U forward
 * [Java + Data Structures + Algorithms](https://www.youtube.com/playlist?list=PLKKfKV1b9e8ps6dD3QA5KFfHdiWj9cB1s) - Apni Kaksha
 * [Java + DSA](https://www.youtube.com/playlist?list=PLfqMhTWNBTe3LtFWcvwpqTkUSlB32kJop) - Apna College (YouTube)
 * [Linked Lists - Level 1](https://www.youtube.com/playlist?list=PL-Jc9J83PIiF5VZmktfqW6WVU1pxBF6l_) - Pepcoding