Add screenshot

SiriusKoan · web-flow · commit 5a8dd11d625a · 2022-06-26T09:09:58.000+08:00
diff --git a/README.md b/README.md
@@ -8,3 +8,6 @@ $ e3schedule -s [session cookie] [-only-in-progress]
 
 - `-s` or `--session` - set session cookie
 - `-only-in-progress` - only show in progress homework
+
+## Screenshot
+![image](https://user-images.githubusercontent.com/26023540/175795251-b78cfb51-0a5c-4dd5-b2aa-3a3d4fefd5e9.png)
