[docs] troubleshooting guide

[MKhalusova]

This PR adds a "Troubleshooting guide" to consolidate all the tips and tools that can be helpful when troubleshooting issues on one page.

What the page includes:

1. Logging. That’s one of the first steps in troubleshooting. Essentially, the content (except API reference) has moved into the troubleshooting guide (with some style updates)
2. Hanging code and timeout errors: addresses the mismatched shape of tensors and introduces the debug mode. The debug.md page was removed.
3. CUDA out of memory (“How to avoid CUDA out of memory” moved here)
4. Non-reproducible results between device setups: briefly covers possible reasons and refers to the existing doc.
5. Performance issues on different GPUs: notes on the limitations of using two GPUs
6. Ask for help: where to get further help

A centralized guide can make it easier to troubleshoot common issues as opposed to multiple docs.

[HuggingFaceDocBuilderDev]

The documentation is not available anymore as the PR was closed or merged.

[muellerzr]

I'm not wondering if these may have more value in the Getting Started or Tutorials area. Or put this at the top of the table of contents for this section

[MKhalusova]

I'm ok with moving it into Tutorials, out of all the suggestions, it feels like the most fitting.

[muellerzr]

Thanks! I did a first passthrough on these, overall they're great!

[muellerzr]

Thanks for centralizing this all into a core doc!

[BenjaminBossan]

Thanks Maria, this is a great addition and hopefully will help many users to come. I left a few small comments.

Also wondering if this would be a good place to mention that kernel issue @muellerzr, maybe in the "Hanging code and timeout errors" section.

[MKhalusova]

Also wondering if this would be a good place to mention that kernel issue @muellerzr, maybe in the "Hanging code and timeout errors" section.

Could you please provide some context about the kernel issue you mentioned?

[BenjaminBossan]

Could you please provide some context about the kernel issue you mentioned?

Users sometimes report hanging processes when using older Linux kernels, e.g. here #1929. I thought this could fit here but it's not a must have/can be added later.

[MKhalusova]

I have addressed the feedback and added:

a) a small section on Early stopping (re: #1940)
b) a small section on Linux kernel issue

[BenjaminBossan]

Thanks for the additions. LGTM.

[muellerzr]

Beautiful! 🤩 Thanks!