Add Day 02 medium level navigation link

Fix formatting and update link for Day 02 programs.

Author: curious-vasavi

README.md

@@ -11,6 +11,12 @@ through day-wise problem solving.
 - **Day 01: Core Number Programs**  
   👉 [View Day 01 Programs](src/number_Programming/core/day_01)
 
+  📁 Medium Level – Number Programming
+
+- Day 02: Medium Number Programs  
+  👉 ([view Day 02 Programs}(src/number_Programming/medium/day_02)
+
+
 ---
 
 ## Repository Structure