readme: add more info to File-formats section about sniff's mime-…

…type detection capabilities

README.md

@@ -228,6 +228,11 @@ The `to` command converts CSVs to `.xlsx`, [Parquet](https://parquet.apache.org)
 
 The `sqlp` command returns query results in CSV, JSON, Parquet & [Arrow IPC](https://arrow.apache.org/docs/format/Columnar.html#ipc-file-format) formats. Polars SQL also supports reading external files directly in various formats with its `read_ndjson`, `read_csv`, `read_parquet` & `read_ipc` [table functions](https://github.com/pola-rs/polars/blob/c7fa66a1340418789ec66bdedad6654281afa0ab/polars/polars-sql/src/table_functions.rs#L9-L36).
 
+The `sniff` command can also detect the mime type of any file with the `--no-infer` or `--just-mime` options, may it be local or remote (http and https schemes supported).
+It can detect more than 120 file formats, including MS Office/Open Document files, JSON, XML, 
+PDF, PNG, JPEG and specialized geospatial formats like GPX, GML, KML, TML, TMX, TSX, TTML.
+See https://docs.rs/file-format/latest/file_format/#reader-features for a complete list.
+
 ### Snappy Compression/Decompression
 
 qsv supports *automatic compression/decompression* using the [Snappy frame format](https://github.com/google/snappy/blob/main/framing_format.txt). Snappy was chosen instead of more popular compression formats like gzip because it was designed for [high-performance streaming compression & decompression](https://github.com/google/snappy/tree/main/docs#readme) (up to 2.58 gb/sec compression, 0.89 gb/sec decompression).