Add ReadLimit to Option structs

Would it be possible to add a field to `AcceptOptions` and to `DialOptions` that sets the read limit on the created connection? It's not as convenient to have to call the `SetReadLimit()`. If the field is 0 then a default limit can be applied.

Is there a need to change the limit dynamically? I mean, why is it a method (i.e. can be called multiple times) vs a field in those option setting structs?