Update API docs to have the details about accelerator metadata in Update results API

[bharathappali]

Thanks @kusumachalasani for pointing this out.

Kruize has recently added a feature [Currently BETA] for Accelerator based recommendation in remote monitoring usecase. For the users to have an idea on the format in which the data needs to be sent to the update results API the current docs needs to be updated with a section which specifies about sending the accelerator data along with the CPU and memory.