Allow the Encoding Object in all locations

There is no reason to restrict use of the `encoding` field of
the Media Type Object to Request Body Objects only.  Not only
does this exclude legitimate use cases of returning multipart
content (particularly as we fix the support for `multipart/mixed`),
it also complicates implementation by requiring the handlingn of
the Media Type Object to be context-aware.

This is a rare change that both simplifies implementation and
adds functionality.

Author: handrews

src/oas.md

@@ -1615,7 +1615,7 @@ See [Working With Examples](#working-with-examples) for further guidance regardi
 | <a name="media-type-schema"></a>schema | [Schema Object](#schema-object) | The schema defining the content of the request, response, parameter, or header. |
 | <a name="media-type-example"></a>example | Any | Example of the media type; see [Working With Examples](#working-with-examples). |
 | <a name="media-type-examples"></a>examples | Map[ `string`, [Example Object](#example-object) \| [Reference Object](#reference-object)] | Examples of the media type; see [Working With Examples](#working-with-examples). |
-| <a name="media-type-encoding"></a>encoding | Map[`string`, [Encoding Object](#encoding-object)] | A map between a property name and its encoding information. The key, being the property name, MUST exist in the schema as a property. The `encoding` field SHALL only apply to [Request Body Objects](#request-body-object), and only when the media type is `multipart` or `application/x-www-form-urlencoded`. If no Encoding Object is provided for a property, the behavior is determined by the default values documented for the Encoding Object. |
+| <a name="media-type-encoding"></a>encoding | Map[`string`, [Encoding Object](#encoding-object)] | A map between a property name and its encoding information. The key, being the property name, MUST exist in the schema as a property. The `encoding` field SHALL only apply when the media type is `multipart` or `application/x-www-form-urlencoded`. If no Encoding Object is provided for a property, the behavior is determined by the default values documented for the Encoding Object. |
 
 This object MAY be extended with [Specification Extensions](#specification-extensions).