Update part2c.md

remove the single quotation marks when set REACT_APP_API_KEY so that users do not have to deal with them in App.js

Author: sailingnn

src/content/2/en/part2c.md

@@ -645,9 +645,9 @@ If you use Open weather map, [here](https://openweathermap.org/weather-condition
 Assuming the api-key is <i>t0p53cr3t4p1k3yv4lu3</i>, when the application is started like so:
 
 ```bash
-REACT_APP_API_KEY='t0p53cr3t4p1k3yv4lu3' npm start // For Linux/macOS Bash
-($env:REACT_APP_API_KEY='t0p53cr3t4p1k3yv4lu3') -and (npm start) // For Windows PowerShell
-set REACT_APP_API_KEY='t0p53cr3t4p1k3yv4lu3' && npm start // For Windows cmd.exe
+REACT_APP_API_KEY=t0p53cr3t4p1k3yv4lu3 npm start // For Linux/macOS Bash
+($env:REACT_APP_API_KEY=t0p53cr3t4p1k3yv4lu3) -and (npm start) // For Windows PowerShell
+set REACT_APP_API_KEY=t0p53cr3t4p1k3yv4lu3 && npm start // For Windows cmd.exe
 ```
 
 you can access the value of the key from the _process.env_ object: