Adding extension for attachments

Thanks, I've made the edits (I think). I've added a specific reference to
parts from the draft doc [1] which defines what a part is.

[1] -
https://tools.ietf.org/html/draft-ietf-appsawg-multipart-form-data-05#section-5

On Wed, Oct 15, 2014 at 11:40 PM, Mike Amundsen <notifications@github.com>
wrote:

> In attachment.md:
>
> > +A client MAY receive a CollectionJson document containing a Write template which accepts attachments which the client can use to send files.
> > +
> > +### Content-type property
> > +This extension defines a new optional property for the template object: `content-type`. The two valid values for `content-type ` are:
> > +
> > +* `multipart/form-data` (this is the one to use for uploading attachments)
> > +* `application/vnd.collection+json` (this is the one to use for sending regular CJ documents) If the content-type property is missing, clients SHOULD use `application/vnd.collection+json` when sending a CJ document. If the content-type property is not supported and/or the provided value is not understood by the client, the client MUST use `application/vnd.collection+json` when sending CJ documents.
> > +
> > +### Attachment property
> > +This extension defines a new property for the data object: `attachment`. This property is only valid for data objects that are children of the template object.
> > +
> > +The two valid values for the `attachment` property:
> > +
> > +* true (treat this data element as an attachment to be uploaded)
> > +* false (treat this data element as a text element) If the client does not support the `attachment` property and/or the value of this property is not understood, the client MUST treat the data element as a text element.
> > +
>
> for the Write Template section[0] - ​replace instances of content-type
> with contentType - replace "compile" with "complies" - normalize the use of
> "NOTE:....." in the Attachment Property section vs. inline text in the
> ContentType section. I like the NOTE format, but it's up to you. If you
> want to talk about body parts, I think you need to identify them in the
> Example. for the Multipart Requests section[1] - normalize references to
> data object, template object, & template data object. - change attachements
> to attachments [0]
> https://github.com/glennblock/extensions/blob/master/attachment.md#write-template
> [1]
> https://github.com/glennblock/extensions/blob/master/attachment.md#mulipart-requests
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/collection-json/extensions/pull/7/files#r18940127>.
>