shape of secondary-key for primary index.
shape of secondary-key for primary index.

secondary-key for primary-index will look-like --- `["<docid>"]`

Change-Id: I3bc94bebbf897bf8b409f1d29d68663c5ae2e7d9
Reviewed-on: http://review.couchbase.org/43473
Reviewed-by: Sarath Lakshman <d41e430501c5d3aeeb2b91142f917f514040f807@couchbase.com>
Reviewed-by: Pratap Chakravarthy <3f7aa3c5f732447448ccfcd013fd9591a9825870@couchbase.com>
Tested-by: Pratap Chakravarthy <3f7aa3c5f732447448ccfcd013fd9591a9825870@couchbase.com>

jchris/indexing,jchris/indexing,jchris/indexing,jchris/indexing