README misdocuments default value for `parse_response_by_content_type`

[geemus]

Looks like this may have changed as of 5.0.0. It previously defaulted to false, but now appears to default to true.

See:

https://github.com/interagent/committee/blob/f6748a5dd84af727c2ed1647b22f54aaa2f6b109/README.md?plain=1#L164

There also appear to be a few of defaulting related things to cleanup that look like: # TODO: delete when 5.0.0 released because default value changed

[unicornzero]

Thank you for reporting this! I'm setting up committee for the first time and your comment helped me get past an issue.

If someone else runs into difficulty with responses of Content-type "application/vnd.api+json", try updating your Committee::Middleware::ResponseValidation options to include parse_response_by_content_type: false

Example error in case someone searches for this:

Committee::InvalidResponse:
       #/components/responses/foobar/content/application~1vnd.api+json/schema expected object, but received String: "{\"data\":{\"type\":\"