Missing Timestamp in ETag support docs

[arkoc]

http://odata.github.io/RESTier/#02-04-ETAG

In Documentation about ETag support missing reference to [Timestamp] attribute. Concurrency checks in EF work not only for entities with [ConcurrencyCheck] attribute but also with [Timestamp].

All versions of docs affected.

[robertmclaws]

I would love to circle back with you and put together a working ETag sample... I've never gotten it to work, and would love to see something functional here so we can fix the docs. Would you be interested in helping out?

[jspuij]

I've got it working. If you want me to write something for the docs. I'll be glad to.

[jspuij]

Fixed in #776