Update doc and add TODO

Author: pitrou

ci/scripts/cpp_test.sh

@@ -184,6 +184,7 @@ if [ "${ARROW_FUZZING}" == "ON" ]; then
     if [ "${ARROW_PARQUET}" == "ON" ]; then
       "${binary_output_dir}/parquet-arrow-fuzz" "${ARROW_TEST_DATA}"/parquet/fuzzing/*-testcase-*
     fi
+    # TODO run CSV fuzz regression tests once we have any
 fi
 
 popd

docs/source/developers/cpp/fuzzing.rst

@@ -29,6 +29,7 @@ fuzz testing on several parts of the Arrow C++ feature set, currently:
 * the IPC stream format
 * the IPC file format
 * the Parquet file format
+* the CSV file format
 
 We welcome any contribution to expand the scope of fuzz testing and cover
 areas ingesting potentially invalid or malicious data.