Wire spec version 2

[rachmatowicz]

Draft version of the wire-spec-v2.
A wire spec does not get into implementation details, so I have tried to give an overall descrption of what the protocol is trying to do and any additional request response data required.

[ropalka]

I just managed to review the diff between v1 & v2 documents. All looks good to me @rachmatowicz .

[rachmatowicz]

I need to add the discovery operation wire spec. This was also omitted from v1.
Added sections for discovery. Fixed a few typos which were causing formatting to be misaligned.

[ropalka]

Reviewed also Discovery request / response amendment. Still LGTM.

[rachmatowicz]

I've made the final updates to this document. I tried to harmonize the content of the sections (using the same section headers in each section, like Message Type, Additional Required Headers, Additional Optional Headers, etc), and added the interoperability headers into the protocol descriptions.

[ropalka]

Reviewed also after the final update of the document - LGTM.

[rachmatowicz]

Just realigned a few fields with no changes to content.

[rachmatowicz]

I have updated the document to remove references to the x-wf-version header which is only used in v1 messages and and added an explanatory note in the changes since v1 section. This can be merged as I won't be making any further changes.

[fl4via]

@rachmatowicz you are the author, and please also update the date and revision

[ropalka]

Thanks @rachmatowicz !