Add .env configuration support

README.md

@@ -1,2 +1,30 @@
 # daily-blackout-check
-check every hour for daily power outage 
+
+Checks planned power outages and sends new notices to an Eitaa chat.
+
+## Setup
+
+1. Create and activate a Python virtual environment, then install dependencies:
+
+   ```sh
+   python -m venv .venv
+   source .venv/bin/activate
+   pip install -r requirements.txt
+   ```
+
+2. Copy the example configuration and replace its placeholder values:
+
+   ```sh
+   cp .env.example .env
+   ```
+
+3. Run the checker:
+
+   ```sh
+   python main.py
+   ```
+
+The `.env` file is ignored by Git so tokens are not committed. Environment
+variables supplied by the shell or GitHub Actions take precedence over `.env`.
+
+`BILL_IDS` accepts one or more comma-separated electricity bill IDs.