docs: 📝 switch readme to markdown

README.md

@@ -0,0 +1,19 @@
+Please add your content into the section folder. It should have the following structure:
+
+(obviously, you should replase sections and subsectionX with the section name and the subsection name)
+
+```bash
+$ tree OCRudoku-first-defense/
+
+OCRudoku-first-defense/
+├── main.txt
+├── README.txt
+└── sections
+    ├── section1
+    │   └── section1.tex
+    └── section2
+        ├── subsection1
+        │   └── subsection2.tex
+        └── subsection2
+            └── subsection2.tex
+```