Fix typos in EventSourceAndCounters.md

docs/EventSourceAndCounters.md

@@ -12,7 +12,7 @@ Similarly, you should have a basic understanding of `EventCounter` and how they
 
 ## Event Patterns
 
-* Add `ILogger` based tracing in all the places you add `EventSource` tracing unless there's a really good reason not to. You can always used the `Trace` level ;).
+* Add `ILogger` based tracing in all the places you add `EventSource` tracing unless there's a really good reason not to. You can always use the `Trace` level ;).
 * `Start`/`Stop` events should have at least one payload value in common that can be used to correlate them. For example, Request ID, Request Path, Action Name, etc.
 * `Error` events should use the `EventLevel.Error` level (which should be obvious I hope ;))
 * `Stop` events should include a `double durationInMilliseconds` payload value with the duration between the `Start` and `End` event in milliseconds.
@@ -98,7 +98,7 @@ Since Event Counters are only actually enabled when the `EventCounterIntervalSec
 There are a number of different "kinds" of event counters in our system. They are characterized by what kind of value is written in the `EventCounter.WriteMetric` call. Counters provide multiple aggregations (Count, Mean, StdDev, Min, Max), and certain aggregations are appropriate for different kinds of counters.
 
 * Counters track the number of times an event occurs. They are written by calling `.WriteMetric(1.0f)` to the counter. The consumer can determine the number of events that occurred over an interval by reading the "Count" aggregation. They should have names combining a plural noun and adjective, like "RequestsStarted"
-* Metrics track a value that changes over time or per "unit" (i.e. per request, per connection, etc.). They are written by calling `.WriteMetric` with the current value of the metric. The consumer can use the aggregates to get data about the metric over time. They should have names combining a singular nouns describing the metric, like "RequestBodySize"
+* Metrics track a value that changes over time or per "unit" (i.e. per request, per connection, etc.). They are written by calling `.WriteMetric` with the current value of the metric. The consumer can use the aggregates to get data about the metric over time. They should have names combining a singular noun describing the metric, like "RequestBodySize"
   * Durations are a Metric that tracks a time duration in milliseconds. They have names ending with "Duration", like "RequestDuration"
 
 ## Full Example