Added content to the readme file

Chandra0505 · web-flow · commit 159674591d14 · 2020-10-01T11:48:57.000+05:30
I've added all the necessary details in the readme file of this project so that anyone can understand how to use this project.
diff --git a/projects/Digital_clock/README.md b/projects/Digital_clock/README.md
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+# Digital Clock using Python and Tkinter
+This script create a digital clock as per the system's current time.
+
+## Library Used
+* tkinter
+* time
+
+### To install required external modules
+* Run `pip install tkinter` 
+
+### How to run the script
+- Execute `python3 digital_clock.py`
+
+### Screenshot/GIF showing the sample use of the script
+
+![Digital Clock Output](https://github.com/Python-World/python-mini-projects/blob/master/projects/Digital_clock/Digital%20Clock.PNG)
