Add policy and default policy

Author: psrbr157@gmail.com

internal/limiter/policy.go

@@ -1 +1,14 @@
-// internal/limiter/policy.go
+package limiter
+
+import "time"
+
+type Policy struct {
+	Limit	 	int
+	Window	 	time.Duration
+	BurstLimit 	int
+}
+
+var DefaultPolicy = Policy{
+	Limit: 100,
+	Window: time.Minute
+}