[Docs] Add more details to profiling docs

[Edenzzzz]

Motivation

Nsys can be burdensome to use for beginners, so added some explanations and moved PyTorch Profiler to show first.

Modifications

Checklist

• Format your code according to the Code Formatting with Pre-Commit.
• Add unit tests as outlined in the Running Unit Tests.
• Update documentation / docstrings / example tutorials as needed, according to Writing Documentation.
• Provide throughput / latency benchmark results and accuracy evaluation results as needed, according to Benchmark and Profiling.

[Edenzzzz]

cc @Fridge003 @zhaochenyang20

[zhaochenyang20]

@Fridge003 and me think it's great.