chore: in .env.example, add the examples to configure DATA_DIR and embedder settings

Author: ksachdeva

.env.example

@@ -10,5 +10,11 @@ ADK_DATABASE_URL=sqlite:///./chatkit.db
 gpt41_agent={"llm":{"model_name": "azure/gpt-4.1", "provider_args" : {"api_key": "xx", "api_base": "", "api_version": "2025-03-01-preview"}}}
 gpt41_mini_agent={"llm":{"model_name": "azure/gpt-4.1-mini", "provider_args" : {"api_key": "xx", "api_base": "", "api_version": "2025-03-01-preview"}}}
 
-
+# Directory to store data (used by Knowledge example)
 DATA_DIR=/workspaces/adk-chatkit/examples/data
+
+# Configuration for the embedding model
+# Other possibilities are openai and azure_openai
+# See EmbedderSettings in examples/backend/src/_config.py
+embedder={"provider_type": "ollama", "model_name": "mxbai-embed-large:latest", "api_endpoint": "http://host.docker.internal:11434"}
+# embedder={"provider_type": "azure_openai", "api_version" : "2025-03-01-preview", "api_deployment" : "text-embedding-3-large", "api_key": "", "model_name": "text-embedding-3-large", "api_endpoint": ""}