[skip ci]Fix a minor mistake (#16966)

Signed-off-by: Nwayblink <anyang.wang@zilliz.com>
Co-authored-by: Nwayblink <anyang.wang@zilliz.com>

CONTRIBUTING.md

@@ -188,7 +188,7 @@ In this case, we are only concerned about the tests with name "SegmentReplica" a
 sub tests with name "segmentFlushed". When running sub tests, the coverage is not concerned.
 
 ```shell
-$ go test ./internale/datanode -run SegmentReplica/segmentFlushed
+$ go test ./internal/datanode -run SegmentReplica/segmentFlushed
 ok  	github.com/milvus-io/milvus/internal/datanode 0.019s
 ```