add model picking docs (#181)

README.md

@@ -14,7 +14,7 @@ Welcome to OpenDevin, an open-source project aiming to replicate [Devin](https:/
 
 ## Work in Progress
 
-OpenDevin is still a work in progress. But you can run the current app to see things working end-to-end.
+OpenDevin is still a work in progress. But you can run the alpha version to see things working end-to-end.
 
 ### Requirements
 * [Docker](https://docs.docker.com/engine/install/)
@@ -37,6 +37,19 @@ npm run start -- --port 3001
 
 You'll see OpenDevin running at localhost:3001
 
+### Picking a Model
+We use LiteLLM, so you can run OpenDevin with any foundation model, including OpenAI, Claude, and Gemini.
+LiteLLM has a [full list of providers](https://docs.litellm.ai/docs/providers).
+
+To change the model, set the `MODEL_NAME` environment variable, as well as the appropriate
+API key based on LiteLLM's [provider documentation](https://docs.litellm.ai/docs/providers).
+
+For example, to run Claude:
+```bash
+export ANTHROPIC_API_KEY="your-api-key"
+export MODEL_NAME="claude-3-opus-20240229"
+```
+
 ## 🤔 What is [Devin](https://www.cognition-labs.com/introducing-devin)?
 
 Devin represents a cutting-edge autonomous agent designed to navigate the complexities of software engineering. It leverages a combination of tools such as a shell, code editor, and web browser, showcasing the untapped potential of LLMs in software development. Our goal is to explore and expand upon Devin's capabilities, identifying both its strengths and areas for improvement, to guide the progress of open code models.