Merge pull request #4267 from char0n/char0n/generating-and-validating-uris

Editorial change: add Header Object to Generating and Validating URIs section

Author: ralfhandl

src/oas.md

@@ -4488,7 +4488,7 @@ This specification normatively cites the following relevant standards:
 Style-based serialization is used in the [Parameter Object](#parameter-object) when `schema` is present, and in the [Encoding Object](#encoding-object) when at least one of `style`, `explode`, or `allowReserved` is present.
 See [Appendix C](#appendix-c-using-rfc6570-based-serialization) for more details of RFC6570's two different approaches to percent-encoding, including an example involving `+`.
 
-Content-based serialization is defined by the [Media Type Object](#media-type-object), and used with the [Parameter Object](#parameter-object) when the `content` field is present, and with the [Encoding Object](#encoding-object) based on the `contentType` field when the fields `style`, `explode`, and `allowReserved` are absent.
+Content-based serialization is defined by the [Media Type Object](#media-type-object), and used with the [Parameter Object](#parameter-object) and [Header Object](#header-object) when the `content` field is present, and with the [Encoding Object](#encoding-object) based on the `contentType` field when the fields `style`, `explode`, and `allowReserved` are absent.
 Each part is encoded based on the media type (e.g. `text/plain` or `application/json`), and must then be percent-encoded for use in a `form-urlencoded` string.
 
 Note that content-based serialization for `form-data` does not expect or require percent-encoding in the data, only in per-part header values.