docs - in README.md, add the note to rename .env.example to .env for simple-app

Author: ksachdeva

README.md

@@ -149,6 +149,11 @@ That said, the way core library is written you can easily replace any component
 your own implementation i.e. your choice of LLM, embedding models etc. Even some of
 the classes as long as they implement the required interface.
 
+**Note**:
+
+Make sure to rename `.env.example` with `.env` if you are using OpenAI or AzureOpenAI
+and fill in the necessary environment variables.
+
 ```bash
 # To generate the index
 # default set azure_openai/gpt4-o/text-embedding-3-small

examples/simple-app/README.md

@@ -10,6 +10,11 @@ Normally `rye sync` at the root of the repo will install all the dependenceis
 
 ## Run
 
+**Note**:
+
+Make sure to rename `.env.example` with `.env` if you are using OpenAI or AzureOpenAI
+and fill in the necessary environment variables.
+
 ```bash
 # assuming you are at the root of the repo
 python examples/simple-app/app/main.py --help