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

docs(caching): a declared primary_key is a row constraint, not the cache key The caching refresh-mode page said a declared `acceleration.primary_key` replaces request metadata as the cache key, and its worked example passed a YAML list. Neither is true. A cache lookup is built from the request alone, so a key over response fields could not serve one even in principle; `primary_key` is a uniqueness constraint on the rows the accelerator stores. And `primary_key` deserializes as a string in every release, so the list form never parsed — the whole Spicepod is rejected at load. The example now projects the response fields it keys on with a `columns:` block and passes the key as a parenthesized string. That projection is only available from v2.0.0, so the 1.10.x and 1.11.x copies drop the example instead and state what a key can name there.

docs(cdc): surface MySQL + MongoDB native CDC; stop listing append-only Kafka as a changes source The global 'Changes Refresh Mode' reference listed PostgreSQL, DynamoDB, Kafka, and Debezium as CDC-capable connectors — but Kafka is append-only (refresh_mode: append, not changes), and MySQL (binlog) and MongoDB (change streams) native CDC were omitted despite having full feature docs. Corrects the connector list, moves Kafka to a clarifying note, and notes that arrow/duckdb/sqlite/cayenne can all be changes sinks. Also advertises native CDC on the MySQL/MongoDB rows of the connector overview matrix (vNext). Versioned 2.1.x/2.0.x carry the same wrong Kafka claim and MongoDB omission (corrected); MySQL CDC is not in those releases, so it is not added there.

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(snapshot refresh mode): the mode never publishes snapshots, even with snapshots: enabled