Add project knowhere in CONTRIBUTING.md (#16036)

Signed-off-by: Nyangxuan <xuan.yang@zilliz.com>

CONTRIBUTING.md

@@ -28,7 +28,7 @@ As for everything else in the project, the contributions to Milvus are governed
 | Suitable for                             | Projects                                                                                                                                                                            | Resources                                                                                           |
 | ---------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------- |
 | Go developers                            | [milvus](https://github.com/milvus-io/milvus), [milvus-sdk-go](https://github.com/milvus-io/milvus-sdk-go)                                                                          |                                                                                                     |
-| CPP developers                           | [milvus](https://github.com/milvus-io/milvus)                                                                                                                                       |                                                                                                     |
+| CPP developers                           | [milvus](https://github.com/milvus-io/milvus), [knowhere](https://github.com/milvus-io/knowhere)                                                                                    |                                                                                                     |
 | Developers interested in other languages | [pymilvus](https://github.com/milvus-io/pymilvus), [milvus-sdk-node](https://github.com/milvus-io/milvus-sdk-node), [milvus-sdk-java](https://github.com/milvus-io/milvus-sdk-java) | [Contributing to PyMilvus](https://github.com/milvus-io/pymilvus/blob/master/CONTRIBUTING.md)       |
 | Kubernetes enthusiasts                   | [milvus-helm](https://github.com/milvus-io/milvus-helm)                                                                                                                             |                                                                                                     |
 | Tech writers and docs enthusiasts        | [milvus-docs](https://github.com/milvus-io/milvus-docs)                                                                                                                             | [Contributing to milvus docs](https://github.com/milvus-io/milvus-docs/blob/v2.0.0/CONTRIBUTING.md) |