### What changes were proposed in this pull request?
This PR proposes to document the way of debugging PySpark. It's pretty much self-descriptive.
I made a demo site to review it more effectively: https://hyukjin-spark.readthedocs.io/en/stable/development/debugging.html
### Why are the changes needed?
To let users know how to debug PySpark applications.
### Does this PR introduce _any_ user-facing change?
Yes, it adds a new page in the documentation about debugging PySpark.
### How was this patch tested?
Manually built the doc.
Closes#29639 from HyukjinKwon/SPARK-32186.
Authored-by: HyukjinKwon <gurwls223@apache.org>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>