Fix AzureOpenAI embeddings documentation example. model -> deployment (#4389)

# Documentation for Azure OpenAI embeddings model

- OPENAI_API_VERSION environment variable is needed for the endpoint
- The constructor does not work with model, it works with deployment.

I fixed it in the notebook.

(This is my first contribution)

## Who can review?

@hwchase17 
@agola

Co-authored-by: Harrison Chase <hw.chase.17@gmail.com>

docs/modules/models/text_embedding/examples/azureopenai.ipynb

@@ -35,7 +35,7 @@
    "source": [
     "from langchain.embeddings import OpenAIEmbeddings\n",
     "\n",
-    "embeddings = OpenAIEmbeddings(model=\"your-embeddings-deployment-name\")"
+    "embeddings = OpenAIEmbeddings(deployment=\"your-embeddings-deployment-name\")"
    ]
   },
   {