add pipenv

README.md

@@ -13,8 +13,16 @@ Solutions for the advent of code 2022
 - After a successful login extract your session token from your browser
 - Create a `.env` file and make sure to export the environment variable below
 - The lib will outomatically work if the environment variable is present
+- `Pipenv` automatically loads `.env` files
 
 ```bash
 $ cat .env
 export AOC_SESSION="53616c..."
 ```
+
+## how to get a pipenv shell
+
+```bash
+$ pipenv install
+$ pipenv shell
+```