docs: file detection using first few bytes disabled on S3 direct upload

[pdurbin]

Preview doc changes here:

• https://dataverse-guide--11035.org.readthedocs.build/en/11035/developers/big-data-support.html#features-that-are-disabled-if-s3-direct-upload-is-enabled
• https://dataverse-guide--11035.org.readthedocs.build/en/11035/api/native-api.html#redetect-file-type

What this PR does / why we need it:

There is confusion about file detection when using S3. See recent discussion between @bseeger and @shlake :

• https://groups.google.com/g/dataverse-community/c/TBx0TTins2k/m/ubHT7B33CAAJ
• https://groups.google.com/g/dataverse-community/c/EYPH_yPpDkI/m/WPjHSDLYBQAJ

[ofahimIQSS]

Proof read, merging PR