cdc: Incorrect/outdated changefeed limitations section

[miretskiy]

Stumbled upon known limitations page
https://www.cockroachlabs.com/docs/v23.1/create-and-configure-changefeeds#known-limitations,
and noticed that we have few out of date limitations listed there:

• Webhook sinks only support emitting JSON. Tracking GitHub Issue — that’s not true; CSV also supported
• There is no concurrency configurability for webhook sinks. Tracking GitHub Issue — not true, we have changefeed.sink_io_workers setting to control this.
• Using a cloud storage sink only works with JSON and emits newline-delimited json files. Tracking GitHub Issue — CSV and Parquet also supported.
• If a changefeed with on_error='pause(https://www.cockroachlabs.com/docs/v23.1/create-changefeed#on-error) is running when a watched table truncated ... angefeed will pause but will not be able to resume reads from that table.... I'm not sure it's a limitation; I think it's working as intended. Perhaps this whole on_error=pause should be deprecated/removed.

Jira issue: CRDB-33610

[blathers-crl]

cc @cockroachdb/cdc