chore: add flow test input files update instructions

crates/committer_cli/benches/committer_bench.rs

@@ -1,5 +1,12 @@
 #![allow(clippy::unwrap_used)]
 
+// This file is for benchmarking the committer flow.
+// The input files for the different benchmarks are downloaded from GCS, using the prefix stored in
+// committer_cli/src/tests/flow_test_files_prefix. In order to update them, generate a new random
+// prefix (the hash of the initial new commit can be used) and update it in the mentioned file.
+// Then upload the new files to GCS with this new prefix (run e.g.,
+// gcloud storage cp LOCAL_FILE gs://committer-testing-artifacts/NEW_PREFIX/tree_flow_inputs.json).
+
 use std::{collections::HashMap, sync::Arc};
 
 use committer::{