Add Weaviate to README (#489)

* add Weaviate to README

* fix

README.md

@@ -48,3 +48,4 @@ Please check out our [Contribution Guidelines](CONTRIBUTING.md) for all the deta
 | [ragas-haystack](integrations/ragas/)                               | Evaluator           | [![PyPI - Version](https://img.shields.io/pypi/v/ragas-haystack.svg)](https://pypi.org/project/ragas-haystack)                                           | [![Test / ragas](https://github.com/deepset-ai/haystack-core-integrations/actions/workflows/ragas.yml/badge.svg)](https://github.com/deepset-ai/haystack-core-integrations/actions/workflows/ragas.yml)                                              |
 | [unstructured-fileconverter-haystack](integrations/unstructured/)   | File converter      | [![PyPI - Version](https://img.shields.io/pypi/v/unstructured-fileconverter-haystack.svg)](https://pypi.org/project/unstructured-fileconverter-haystack) | [![Test / unstructured](https://github.com/deepset-ai/haystack-core-integrations/actions/workflows/unstructured.yml/badge.svg)](https://github.com/deepset-ai/haystack-core-integrations/actions/workflows/unstructured.yml)                         |
 | [uptrain-haystack](integrations/uptrain/)                           | Evaluator           | [![PyPI - Version](https://img.shields.io/pypi/v/uptrain-haystack.svg)](https://pypi.org/project/uptrain-haystack)                                       | [![Test / uptrain](https://github.com/deepset-ai/haystack-core-integrations/actions/workflows/uptrain.yml/badge.svg)](https://github.com/deepset-ai/haystack-core-integrations/actions/workflows/uptrain.yml)                                        |
+| [weaviate-haystack](integrations/weaviate/)                           | Document Store      | [![PyPI - Version](https://img.shields.io/pypi/v/weaviate-haystack.svg)](https://pypi.org/project/weaviate-haystack)                                       | [![Test / weaviate](https://github.com/deepset-ai/haystack-core-integrations/actions/workflows/weaviate.yml/badge.svg)](https://github.com/deepset-ai/haystack-core-integrations/actions/workflows/weaviate.yml)                                         |