Update README

README.md

@@ -32,9 +32,11 @@ pip install -r requirements.txt
 ```
 
 3. Prepare environment keys:
-```
-# Credentials for GPT-4 Model
-OPENAI_API_KEY=<openai_api_key>
+```dosini
+# Credentials for LLM Models
+OPENAI_API_KEY=<api_key>
+GOOGLE_API_KEY=<api_key>
+PERPLEXITY_API_KEY=<api_key>
 
 # (Optional) Tracking your extraction process with LangSmith
 LANGCHAIN_TRACING_V2='true'