[Update] add expire check interval doc in README.md

README.md

@@ -312,6 +312,28 @@ added key: 1
 added key: 2
 ```
 
+## Interval
+### Expire check interval
+```go
+func main () {
+  gc := gcache.New(10).
+    LRU().
+    EvictedFunc(func(key, value interface{}) {
+        fmt.Printf("key: [%v] evicted\n", key)
+    }).
+    ExpireCheckInterval(300 * time.Millisecond).
+    Build()
+
+  _ = gc.SetWithExpire(1, 1, time.Second)
+
+  time.Sleep(time.Second * 2)
+}
+```
+
+```
+key: [1] evicted
+```
+
 # Author
 
 **Jun Kimura**