Add versioned docs for v2.1 (#1903) Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Add versioned docs for v2.1 (#1903) Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

docs(vectors): flag the Elasticsearch engine as Enterprise in the listing The Elasticsearch vector engine is gated behind spiced's `elasticsearch` feature, which is not in the default OSS feature set (bin/spiced/Cargo.toml), and its dedicated page already carries the Enterprise edition callout. The Vector Engines listing table did not label it, unlike the data-connectors index which appends "(Spice.ai Enterprise)" to the description.

docs(s3_vectors): document batch_write_rows, spill_writes, iam_role_source Three parameters in the engine's `PARAMETERS` array (crates/runtime/src/embeddings/index/s3/mod.rs) were never documented: - s3_vectors_batch_write_rows (v1.9+, default 100000 = DEFAULT_BATCH_WRITE_ROWS) - s3_vectors_spill_writes (v1.11+, default false; ignored with a warning when partition_by is set) - s3_vectors_aws_iam_role_source (v2.0+, auto | metadata | env, default auto; bypassed entirely when an access key and secret are set) Each row is added only to the snapshots whose release actually declares the parameter, verified against PARAMETERS at each tag.