updated readme

Author: astratakis

README.md

@@ -1,3 +1,20 @@
 # Open-CP API
 
-The backend of Open-CP
+- `/api`
+  - 🔐 `/auth`
+    - `POST /token` → Generate token
+  - 📘 `/problemset`
+    - `GET /` → Get all problems
+    - `POST /` → Create a problem
+    - `GET /<problem_id>` → Get problem
+    - `PATCH /<problem_id>` → Update problem
+    - `DELETE /<problem_id>` → Delete problem
+    - `GET /<problem_id>/submissions` → Get submissions
+    - `GET /<problem_id>/submissions/<id>` → Get a submission
+    - `POST /submit/<problem_id>` → Submit code
+  - 👤 `/users`
+    - `GET /` → Get all users
+    - `POST /` → Create user
+    - `GET /<user_id>` → Get user
+    - `PATCH /<user_id>` → Update user
+    - `DELETE /<user_id>` → Delete user