feat(LRUCacheDemo): implement simple LRU cache using LinkedHashMap

What
- Added generic `LRUCacheDemo<K, V>` class extending LinkedHashMap.
- Configured `accessOrder=true` to reorder entries based on usage.
- Overrode `removeEldestEntry()` to evict least recently used element when capacity exceeded.
- Added a demo in `main()` with a student marks example.

Why
- Demonstrates how LinkedHashMap can be leveraged to build an **LRU cache** with minimal code.
- Useful for scenarios like caching results, database lookups, or frequently accessed data with limited memory.

How
- Constructor sets custom capacity and calls super with access-order enabled.
- Each `put()` or `get()` operation moves the accessed key to the end of the order.
- When size > capacity, the eldest (least recently used) entry is evicted automatically.
- Demo: inserted 5 student entries with capacity = 3 to illustrate eviction.

Logic
1. Insert "Bob", "Alice", "Ram" → cache full: ["Bob", "Alice", "Ram"]
2. Update "Bob" → reorders to most recent: ["Alice", "Ram", "Bob"]
3. Insert "Vipul" → capacity exceeded → removes eldest ("Alice"): ["Ram", "Bob", "Vipul"]

Real-life applications
- Browser history or session caching.
- Database query result cache.
- Image/object caching in web apps or mobile apps.
- Any system where **least recently used** data should be automatically discarded.

Signed-off-by: https://github.com/Someshdiwan <[email protected]>

Author: Someshdiwan

Section25CollectionFramework/src/HashMapDemo/LinkedHashMapDemo/LRUCache.java renamed to Section 25 Collections Frameworks/Map Interface/Linked HashMap/LRU Cache/src/LRUCacheDemo.java

@@ -1,12 +1,10 @@
-package HashMapDemo.LinkedHashMapDemo;
-
 import java.util.LinkedHashMap;
 import java.util.Map;
 
-public class LRUCache<K, V> extends LinkedHashMap<K, V> {
+public class LRUCacheDemo<K, V> extends LinkedHashMap<K, V> {
     private int capacity;
 
-    public LRUCache(int capacity) {
+    public LRUCacheDemo(int capacity) {
         super(capacity, 0.75f, true);
         this.capacity = capacity;
     }
@@ -17,7 +15,8 @@ protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
     }
 
     public static void main(String[] args) {
-        LRUCache<String, Integer> studentMap = new LRUCache<>(3);
+        LRUCacheDemo<String, Integer> studentMap = new LRUCacheDemo<>(3);
+
         studentMap.put("Bob", 99);
         studentMap.put("Alice", 89);
         studentMap.put("Ram", 91);
@@ -27,8 +26,8 @@ public static void main(String[] args) {
         System.out.println(studentMap);
     }
 }
-/*
-the most recently accessed element moves to the end. This method ensures that the eldest entry (least recently used)
+
+/* the most recently accessed element moves to the end. This method ensures that the eldest entry (least recently used)
 is removed once the cache exceeds the given capacity.
 
 studentMap.put("Bob", 99);   ["Bob"]