User Guide: UploadedFile Class

[MGatner]

The User Guide has some misinformation (https://codeigniter4.github.io/CodeIgniter4/libraries/uploaded_files.html#other-file-info) about the UploadedFile class, which does not actually have getClientType() (should probably read getClientMimeType(). Also falling back to getType() gives "file, link, or directory" - probably meant to say getMimeType().