feat: adding a Summary type in metrics package

metrics/metrics.go

@@ -23,3 +23,12 @@ type Histogram interface {
 	With(labelValues ...string) Histogram
 	Observe(value float64)
 }
+
+// Summary describes a metric that provides a statistical summary of observations, 
+// focusing on quantiles and percentiles. An example is tracking HTTP response times, 
+// allowing for analysis of performance metrics. The Summary interface enables 
+// collection of observations with associated label values.
+type Summary interface {
+	With(labelValues ...string) Summary
+	Observe(value float64)
+}