CI: add warning when not in pandas dev and running stubtest
- [x] closes #48260
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
Thanks for the review. I resolved the comments you mentioned however, I noticed that the link you posted doesn't include the command to skip stubtest over [here](https://pandas.pydata.org/pandas-docs/stable/development/contributing_codebase.html#validating-type-hints) compared to the one we have over [here](https://github.com/pandas-dev/pandas/blob/main/doc/source/development/contributing_codebase.rst#validating-type-hints)

Perhaps, there needs to be another task created for it? Or is it being done in another PR? > Thanks for the review. I resolved the comments you mentioned however, I noticed that the link you posted doesn't include the command to skip stubtest over [here](https://pandas.pydata.org/pandas-docs/stable/development/contributing_codebase.html#validating-type-hints) compared to the one we have over [here](https://github.com/pandas-dev/pandas/blob/main/doc/source/development/contributing_codebase.rst#validating-type-hints)
> 
> Perhaps, there needs to be another task created for it? Or is it being done in another PR?

The doc updates in https://github.com/pandas-dev/pandas/pull/48240 will be reflected on the website soon. We have a CI job that updates the docs (will be applied to versions >= 1.5) Thanks @ambujpawar 