Updated the return type section of to_datetime 
Updated the return type section of to_datetime to include list-like mixed timezone inputs

- [x] closes #42229
- [x] tests added / passed
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [x] whatsnew entry - Updated the return type section of to_datetime to include list-like mixed timezone inputs

@mroeschke - updated as per you suggestion  Removed the additional line , Thanks for patience and feedback @mroeschke  Thanks @prabha-git  Hi @prabha-git and @mroeschke ! It seems that the resulting comment is half/half (half speaking about timezone, half speaking about time offset...). Therefore I created https://github.com/pandas-dev/pandas/pull/42494 to complete this PR.
