message: Update MetricKey.ts
  Fixed typo
diff: @@ -4,7 +4,7 @@ export type MetricKeySym = typeof MetricKeySym
  /**
  * A `MetricKey` is a unique key associated with each metric. The key is based
  * on a combination of the metric type, the name and tags associated with the
  - * metric, and any other information to describe a a metric, such as the
  + * metric, and any other information to describe a metric, such as the
  * boundaries of a histogram. In this way, it is impossible to ever create
  * different metrics with conflicting keys.
  *
  