adding readmes

lru/README.md

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+# LRU Cache 
+
+This is a simple implementation of a Least Recently Used (LRU) Cache in Go.
+
+An LRU Cache will evict the oldest used key whenever the cache gets full.
+
+Example usage
+```go
+capacity := 100
+cache := lru.NewCache(capacity)
+cache.Set("im a key", "im a value")
+val := cache.Get("im a key")
+println(val)
+```