Add instructions to set SECRET_KEY environment variable

Author: lulunac27a

README.md

@@ -6,6 +6,6 @@ This app is an endless task list application with levels and experience points (
 
 1. Clone the repository.
 2. Install dependencies: `pip install -r requirements.txt`.
-3. Set `SECRET_KEY` environment variable.
+3. Set `SECRET_KEY` environment variable. On Windows: use `setx` command in Command Prompt like `setx SECRET_KEY "your_secret_key"`. On macOS and Linux: use `export` command in terminal like `export SECRET_KEY="your_secret_key"`.
 4. Run the app `python app.py`.
 5. Open `localhost:8081` on your web browser.

docs/index.md

@@ -6,6 +6,6 @@ This app is an endless task list application with levels and experience points (
 
 1. Clone the repository.
 2. Install dependencies: `pip install -r requirements.txt`.
-3. Set `SECRET_KEY` environment variable.
+3. Set `SECRET_KEY` environment variable. On Windows: use `setx` command in Command Prompt like `setx SECRET_KEY "your_secret_key"`. On macOS and Linux: use `export` command in terminal like `export SECRET_KEY="your_secret_key"`.
 4. Run the app `python app.py`.
 5. Open `localhost:8081` on your web browser.