add proper way to install and run in the README after the changes from #60 (#76)

README.md

@@ -17,14 +17,15 @@ GPT Engineer is made to be easy to adapt, extend, and make your agent learn how
 ## Usage
 
 **Setup**:
-
-- `pip install -r requirements.txt`
+- `git clone https://github.com/AntonOsika/gpt-engineer.git`
+- `cd gpt-engineer`
+- `pip install .`
 - `export OPENAI_API_KEY=[your api key]` with a key that has GPT4 access
 
 **Run**:
 - Create a new empty folder with a `main_prompt` file (or copy the example folder `cp -r example/ my-new-project`)
 - Fill in the `main_prompt` in your new folder
-- Run `python main.py my-new-project`
+- Run `gpt-engineer my-new-project`
 
 **Results**:
 - Check the generated files in my-new-project/workspace