Add Parrable ID submodule docs

[icflournoy]

Adds documentation for the forthcoming Parrable ID system submodule.

[bretg]

There are a number of ID sub-modules pending -- there will almost certainly be collisions to fix by the time this is merged, but it looks ok other than needing to know how you want to appear in the OpenRTB. Search for 'eids' in the doc.

[jdwieland8282]

mind adding an example, of how prebid server adapters need to be updated if they want to consume this value. Others have used something like { "source": "parrable.com", "uids": [{ "id": "11111111" }] }

[justinegreene]

@bretg and @jdwieland8282, Thank you for the feedback. With respect to openRTB are you referring to bidders with prebid server adapters. The snippet above appears to be from the Prebid server section of the Docs.

On a related note, we are not clear how to modify or inform prebid server to include our cookies in the openRTB object. We can certainly extend the docs, but how does prebid server know to pickup the storage that we have configured in prebid.js?

[jdwieland8282]

Hey @justinegreene sorry yes I was referring to prebid server adapters, from a documentation standpoint this docs PR should describe how PB server adapters should be prepared to read your id. wrt, your question about modifying prebid server prebid/Prebid.js#4178 (comment)

[eyas-ranjous]

@bretg @jdwieland8282 all reviews addressed in this PR. please consider merging. thanks.

[jdwieland8282]

thanks for adding, looks good.

[bretg]

resolved conflicts after merging liveintent. merging this now