docs(tcp): MPTCP join and option makers lack Raises, Quick-Start rate lacks unit and versionchanged #2235

Is your feature request related to a problem? Please describe.
Some docstrings leave out facts the code depends on:

• TCP._make_mptcp_join raises ProtocolError when the segment's flags are neither SYN, SYN/ACK nor ACK. On origin/main, TCP(options=[(Option.Multipath_TCP, {'subtype': MPTCPOption.MP_JOIN})], syn=False, ack=False) raises ProtocolError: TCP: [OptNo 30] 1: invalid flags combination. It is the only maker in the module that raises and has no Raises: section; the _make_mptcp_capable, _make_mptcp_dss, _make_mptcp_addaddr and _make_mode_timeout makers all have one.
• TCP._make_tcp_options raises whatever its option makers raise (the _make_mptcp_* and _make_mode_timeout ones), but it has no Raises: section either. _read_tcp_options does have one.
• Data_QuickStartResponse.req_rate holds an int since fix(tcp): Quick-Start rate parses as float and a Fast Open cookie request as None, against their annotations #2167 (fix(tcp): keep Quick-Start rate an int and a Fast Open cookie request bytes (#2167) #2185) where it held a float such as 80.0, but it has no versionchanged and its comment (Rate request.) gives no unit. FastOpenCookie got a versionchanged in the same PR. The IPv4, HOPOPT and IPv6-Opts Quick-Start data models (rate, Rate request/report.) changed in the same way and have the same gap.

Describe the solution you'd like
Add Raises: ProtocolError: If the flags are none of SYN, SYN/ACK and ACK. to _make_mptcp_join. Add Raises: ProtocolError: If an option maker rejects its option. to _make_tcp_options. Change each Quick-Start rate comment to say it is in kbps (40 * 2 ** N, 0 for N = 0), and add a .. versionchanged:: 1.5.0 to each model saying the rate is an int where it was a float (#2167).

Additional context
The unit is stated only in the makers' rate (in kbps) argument docs, not on the data models that users read.