Add docs for using google llms (#1321)

docs/guides/GoogleLLMs.md

@@ -0,0 +1,26 @@
+# Google Gemini/Vertex LLM Guide
+
+# 1. Completion
+
+OpenDevin uses LiteLLM for completion calls. The following resources are relevant for using OpenDevin with Google's LLMs
+
+- [Gemini - Google AI Studio](https://docs.litellm.ai/docs/providers/gemini)
+- [VertexAI - Google Cloud Platform](https://docs.litellm.ai/docs/providers/vertex)
+
+
+## Gemini - Google AI Studio Configs
+
+To use Gemini through Google AI Studio when running the OpenDevin Docker image, you'll need to set the following environment variables using `-e`:
+```
+GEMINI_API_KEY="<your-google-api-key>"
+LLM_MODEL="gemini/gemini-1.5-pro"
+```
+
+## Vertex AI - Google Cloud Platform Configs
+To use Vertex AI through Google Cloud Platform when running the OpenDevin Docker image, you'll need to set the following environment variables using `-e`:
+```
+GOOGLE_APPLICATION_CREDENTIALS="<json-dump-of-gcp-service-account-json>"
+VERTEXAI_PROJECT="<your-gcp-project-id>"
+VERTEXAI_LOCATION="<your-gcp-location>"
+LLM_MODEL="vertex_ai/<desired-llm-model>"
+```