Add some Advanced ML courses (#408)

* Add UT Dallas CS 7301 (SP21)

* Add Harvard CS 229br (SP21)

Author: butter1125

README.md

@@ -580,6 +580,7 @@ Table of Contents
   - [Trustworthy Machine Learning - Winter Semester 2024-2025, University of Tübingen](https://scalabletrustworthyai.github.io/courses/tml_winter_2425/)
   - [ETH Zürich Advanced Machine Learning fall 2019, by Joachim M. Buhmann](https://video.ethz.ch/lectures/d-infk/2019/autumn/252-0535-00L.html)
   - [CS 159 Advanced Topics in Machine Learning, Spring 2021 - Caltech](https://1five9.github.io/)
+  - [CS 229br Advanced Topics in the theory of machine learning, Spring 2021 - Harvard](https://boazbk.github.io/mltheoryseminar/cs229br.html)
 
 - #### **Natural Language Processing**
   - [CS 224N -Natural Language Processing with Deep Learning - Stanford University](http://web.stanford.edu/class/cs224n/) ([Lectures -  Winter 2019](https://youtube.com/playlist?list=PLoROMvodv4rOhcuXMZkNm7j3fVwBBY42z)) ([Lectures -  Winter 2021](https://youtube.com/playlist?list=PLoROMvodv4rOSH4v6133s9LFPRHjEmbmJ)) ([Lectures - Spring 2024](https://www.youtube.com/playlist?list=PLoROMvodv4rOaMFbaqxPDoLWjDaRAdP9D))
@@ -639,6 +640,7 @@ Table of Contents
   - [Optimisation for Machine Learning: Theory and Implementation (Hindi) - IIT](https://www.youtube.com/playlist?list=PLyqSpQzTE6M-pmLzCoMu_ANU6atEFyyJl)
   - [Rochester DSCC 435 Optimization for Machine Learning fall 2023, by Jiaming Liang](https://www.youtube.com/playlist?list=PLuJY91x7h5orCtyh6mChurVQ2ZZef9qPF)
   - [Princeton ELE539/COS512 Optimization for Machine Learning spring 2021, by Chi Jin](https://sites.google.com/view/cjin/teaching/ece539cos512-2021-ver)
+  - [UT Dallas CS 7301 Advanced Topics in Optimization for Machine Learning spring 2021, by Rishabh Iyer](https://github.com/rishabhk108/AdvancedOptML) ([YouTube](https://www.youtube.com/playlist?list=PLGod0_zT9w92_evaYrf3-rE67AmgPJoUU))
   - [EE364a: Convex Optimization I - Stanford University](https://www.youtube.com/playlist?list=PLoROMvodv4rMJqxxviPa4AmDClvcbHi6h)
   - [10-725 Convex Optimization, Spring 2015 - CMU](http://www.stat.cmu.edu/~ryantibs/convexopt-S15/)
   - [10-725 Convex Optimization: Fall 2016 - CMU](http://www.stat.cmu.edu/~ryantibs/convexopt/)