Removing obsolete metrics guide

Author: robscott

mkdocs.yml

@@ -60,7 +60,6 @@ nav:
     - User Guides:
       - Getting started: guides/index.md
       - Adapter Rollout: guides/adapter-rollout.md
-      - Metrics: guides/metrics.md
     - Implementer's Guide: guides/implementers.md
   - Performance:
     - Benchmark: performance/benchmark/index.md