Update readme.md: fix modulino buttons img

Author: leonardocavagnis

Diff for: docs/readme.md

@@ -41,7 +41,7 @@ modulino_name.begin();  // Initialize the ModulinoType module
 ### ModulinoButtons
 Manages the state of three buttons and controls their associated LED states. You can read the state of each button and send commands to turn the LEDs on/off.
 
-![Modulino Buttons](./images/modulino-buttons.jpg)
+![Modulino Buttons](./images/modulino-buttons.jpeg)
 
 ```cpp
 ModulinoButtons buttons;
@@ -178,4 +178,4 @@ The API documentation can be found [here](./api.md).
 
 ## License
 
-This library is released under the [MPL-2.0 license](../LICENSE).
+This library is released under the [MPL-2.0 license](../LICENSE).