Revert documentation changes to parquet_scans.md

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: andygrove

docs/source/contributor-guide/parquet_scans.md

@@ -37,13 +37,9 @@ implementation:
 
 - Leverages the DataFusion community's ongoing improvements to `DataSourceExec`
 - Provides support for reading complex types (structs, arrays, and maps)
-- Delegates Parquet decoding to native Rust code rather than JVM-side decoding
+- Removes the use of reusable mutable-buffers in Comet, which is complex to maintain
 - Improves performance
 
-> **Note on mutable buffers:** Both `native_comet` and `native_iceberg_compat` use reusable mutable buffers
-> when transferring data from JVM to native code via Arrow FFI. The `native_iceberg_compat` implementation uses DataFusion's native Parquet reader for data columns, bypassing Comet's mutable buffer infrastructure entirely. However, partition columns still use `ConstantColumnReader`, which relies on Comet's mutable buffers that are reused across batches. This means native operators that buffer data (such as `SortExec` or `ShuffleWriterExec`) must perform deep copies to avoid data corruption.
-> See the [FFI documentation](ffi.md) for details on the `arrow_ffi_safe` flag and ownership semantics.
-
 The `native_datafusion` and `native_iceberg_compat` scans share the following limitations:
 
 - When reading Parquet files written by systems other than Spark that contain columns with the logical type `UINT_8`