Update README.md

Author: mafe72

README.md

@@ -1,4 +1,7 @@
 # 3D Printer Filament Runout Sensor
+
+![GitHub issues](https://img.shields.io/github/issues-raw/mafe72/3D-Printer-Filament-Runout-Sensor?logo=Github&style=for-the-badge)
+
 This is a low filament detector base on the ATtiny13 – 8-bit AVR Microcontroller compatible with all 3d printers. When the filament runs out the sensor will sound the alarm and flash the RGB LED; with the proper firmware modifications and GCode, the sensor will pause your printer giving you time to reload your filament.
 
 [![Watch the demo video](pictures/video_shot.png)](https://www.youtube.com/embed/Nork3BS47Sg)
@@ -129,4 +132,4 @@ Basic Hardware Usage
 
 Basic Maintenance
 -----------------
-This sensor contains a limit switch and dust or debris can cause false or changing readings. Clean dust by blowing on the sensor or disassembly to clean the limit switch. Monitor wear and tear of the 3D printer sensor's enclosure as this can cause false positives triggering the sensor.
+This sensor contains a limit switch and dust or debris can cause false or changing readings. Clean dust by blowing on the sensor or disassembly to clean the limit switch. Monitor wear and tear of the 3D printer sensor's enclosure as this can cause false positives triggering the sensor.