Update readme and .env example

Author: yhyu13

.env.example

@@ -0,0 +1,5 @@
+OPENAI_API_KEY=sk-XXXX
+OPENAI_BASE_URL=https://api.openai.com/v1
+API_PORT=3002
+WEB_PORT=3003
+SNAKEMQ_PORT=3004

README.md

@@ -11,8 +11,10 @@ Read the [blog post](https://ricklamers.io/posts/gpt-code) to find out more.
 Open a terminal and run:
 
 ```
-$ pip install gpt-code-ui
-$ gptcode
+cp .env.example .env
+make compile_frontend
+pip install gpt-code-ui
+gptcode
 ```
 
 ## User interface