Update docs/system/container-metrics.md

Co-authored-by: Helen <56097766+heyams@users.noreply.github.com>

docs/system/container-metrics.md

@@ -9,7 +9,7 @@ linkTitle: Container
 ## Container Metrics
 
 This document describes instruments and attributes for common container level
-metrics in OpenTelemetry. Collected from technology-specific,
+metrics in OpenTelemetry. These metrics are collected from technology-specific,
 well-defined APIs (e.g. Kubelet's API or container runtimes).
 
 ### Metric: `container.cpu.time`