bug: accept header vs format query param precedence

[SgtPooki]

specs/src/http-gateways/path-gateway.md

Lines 227 to 240 in f216056

	### `format` (request query parameter)
	Optional, `format=<format>` can be used to request specific response format.
	This is a URL-friendly alternative to sending an [`Accept`](#accept-request-header) header.
	These are the equivalents:
	- `format=raw` → `Accept: application/vnd.ipld.raw`
	- `format=car` → `Accept: application/vnd.ipld.car`
	- `format=tar` → `Accept: application/x-tar`
	- `format=dag-json` → `Accept: application/vnd.ipld.dag-json`
	- `format=dag-cbor` → `Accept: application/vnd.ipld.dag-cbor`
	- `format=json` → `Accept: application/json`
	- `format=cbor` → `Accept: application/cbor`
	- `format=ipns-record` → `Accept: application/vnd.ipfs.ipns-record`

We should clarify which takes precedence. Adin pointed me to https://github.com/ipfs/boxo/blob/4c3a1f2f343637b615c26a27a55afa12dd5aaed5/gateway/handler.go#L620-L621 which says Accept header should take priority.

// First, inspect Accept header, as it may not only include content type, but also optional parameters.
// such as CAR version or additional ones from IPIP-412.