Updated Core Frontend Onboarding (markdown)

Core-Frontend-Onboarding.md

@@ -1,29 +1,29 @@
 New to developing PyTorch? We've got you covered.
 
-Unit 1: PyTorch Basics
+### Unit 1: PyTorch Basics
 - [Developer Environment Setup](https://github.com/pytorch/pytorch/wiki/PyTorch-Basics#development-setup)
 - [Learn about where and how PyTorch is used](https://github.com/pytorch/pytorch/wiki/PyTorch-Basics#learn-about-how-to-use-pytorch)
 
-Unit 2: Tensors, Operators, and Testing
+### Unit 2: Tensors, Operators, and Testing
 - [Tensor and Operator Basics](https://github.com/pytorch/pytorch/wiki/Tensor-and-Operator-Basics)
 - [[Running and writing tests|Running-and-writing-tests]]
 - [Tensor Views Lab](https://colab.research.google.com/drive/1rJP2aw-f5Iwqwri0_Ei_OI8_esh1Nyeq#scrollTo=LpTEuP0JZzav&line=1&uniqifier=1)
 
-Unit 3: Autograd
+### Unit 3: Autograd
 - [Autograd basics](https://github.com/pytorch/pytorch/wiki/Autograd-Basics)
 - [Autograd Lab](https://github.com/pytorch/pytorch/wiki/Autograd-Onboarding-Lab)
 
-Unit 4: Dispatcher, Structured Kernels, and Codegen
+### Unit 4: Dispatcher, Structured Kernels, and Codegen
 - [[Dispatcher and Python bindings|PyTorch-dispatcher-walkthrough]]
 - [Codegen and Structured Kernels Lab](https://github.com/pytorch/pytorch/wiki/Codegen-and-Structured-Kernels)
 
-Unit 5: torch.nn
+### Unit 5: torch.nn
 - [[nn|nn-Basics]], [[C++|Cpp-API-Quick-Walkthrough]]
 - [Modules Lab](https://github.com/pytorch/pytorch/wiki/Module-Onboarding-Lab)
 
-Unit 6: CUDA basics
+### Unit 6: CUDA basics
 - [[CUDA-basics]]
 - [CUDA Perf Lab (internal-only)](https://github.com/pytorch/pytorch/wiki/CUDA-basics#debugging-and-profiling-tips)
 
-Unit 7: Data (Optional)
+### Unit 7: Data (Optional)
 - [[data|Data-Basics]]