Corrected v2 image sharing documentation.

corrected request body for POST to /v2/.../members
removed GET /v2/images/{imageId}/members/{memberId} (call not implemented)

Change-Id: Iafbba48c7d5e8b8b38e77b7ead216d0e7e235cb2
Closes-Bug: #1229351
Merge "Corrected v2 image sharing documentation."