Docs: foreach_record example calls a nonexistent method (positional record type)

[tbeason]

Line refs are against the registered v0.2.0 tarball.

Problem

docs/src/guide/historical.md ("Streaming records: foreach_record") shows:

foreach_record(client, DBN.TradeMsg;
    dataset = "XNAS.ITCH", schema = Schema.TRADES, ...) do trade
    ...
end

i.e. a positional record-type argument after client. The actual method (src/historical/timeseries.jl:111) is:

foreach_record(f, c::Historical; dataset, schema, ..., record_type = nothing)

There is no positional-type method, so the documented call raises a MethodError. The surrounding prose ("The first argument after client is the concrete record type...") is wrong too; the type is inferred from schema by default and overridable via the record_type kwarg.

Suggested fix

Update the example to:

foreach_record(client;
    dataset = "XNAS.ITCH", schema = Schema.TRADES,
    symbols = ["AAPL"],
    start_dt = DateTime(2024, 1, 2, 14, 30),
    end_dt   = DateTime(2024, 1, 2, 20, 0)) do trade
    n_trades[] += 1
end

and fix the paragraph below it. A doctest would prevent regression.