Add LinkedPremises to Benchmark.md

Add LinkedPremises child element to Benchmark element

Overview

This proposal is to add the auc:LinkedPremises child element to the auc:Benchmark element.

Justification

As discussed in #152, there is a need to associate benchmarking data with specific premises and floor areas.

Implementation

1. Add auc:LinkedPremises child element to auc:Benchmark element.

References

N/A