update Readme with some intuitive images

README.md

@@ -2,11 +2,23 @@
 
 [![Playwright Tests](https://github.com/conlacda/useful-atcoder/actions/workflows/playwright.yml/badge.svg)](https://github.com/conlacda/useful-atcoder/actions/workflows/playwright.yml)
 
+## Some features
+### Mark solved problems
+![mark-solved-problems.png](images/mark-solved-problems.png)
+
+### Add more test cases to problem statement
+![add-test-cases.png](images/add-test-cases.png)
+
+### Copy, download test cases and debug your code with those test cases
+![copy-download-debug.png](images/copy-download-debug.png)
+
+### Debug with custom test
+Click one of the <svg xmlns="http://www.w3.org/2000/svg" width="1.5em" height="1.5em" viewBox="0 0 32 32" id="debug-10" style="cursor: pointer;"><path fill="currentColor" d="m29.83 20l.34-2l-5.17-.85v-4.38l5.06-1.36l-.51-1.93l-4.83 1.29A9 9 0 0 0 20 5V2h-2v2.23a8.81 8.81 0 0 0-4 0V2h-2v3a9 9 0 0 0-4.71 5.82L2.46 9.48L2 11.41l5 1.36v4.38L1.84 18l.32 2L7 19.18a8.9 8.9 0 0 0 .82 3.57l-4.53 4.54l1.42 1.42l4.19-4.2a9 9 0 0 0 14.2 0l4.19 4.2l1.42-1.42l-4.54-4.54a8.9 8.9 0 0 0 .83-3.57ZM15 25.92A7 7 0 0 1 9 19v-6h6ZM9.29 11a7 7 0 0 1 13.42 0ZM23 19a7 7 0 0 1-6 6.92V13h6Z"></path></svg> buttons you see above and a custom test page should be opened. Your submission code and input/output should be filled in.
+
+![custom-page-source-code.png](images/custom-page-source-code.png)
+![custom-page-in-out.png](images/custom-page-in-out.png)
+
 ## Features I think I should implement
-* [x] Add test cases to a problem statement
-* [x] Mark solved problems
-* [x] Debug with custom test page
-* [x] Add copy, download and debug button to the submission page.
 * [] Predict rating during a contest
 * [] Add cronjob to download test cases
 * [] Add setup page