docs: Update shell.md: Document that shell.trashItem requires backslashes
In Windows many functions relating to files (e.g. shell.openItem, the Node fs functions, as well as native Win32 APIs) will accept either type of slash / or \ as a folder separator.
shell.trashItem does not work with / as folder separator in Windows. This documentation change explains that.
See also:
https://github.com/electron/electron/issues/28831
Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: sam marshall <s.marshall@open.ac.uk>