feat(docs): README.md update and branding

Signed-off-by: Soubhik Kumar Gon <b422056@iiit-bh.ac.in>

Author: zakhaev26

README.md

@@ -1 +1,18 @@
-# fast-hash
+<p align="center">
+  <img src="media/fast-hash-banner.png" alt="FastHash Banner" width="100%">
+</p>
+
+# FastHash
+
+**FastHash** is a lightweight, fast, and minimal in-memory key-value store built in modern C++.  
+It is inspired by Redis and designed for learning, performance, and extensibility.
+
+---
+
+## Features
+
+- In-memory key-value storage
+- TTL support with automatic expiration
+- Thread-safe operations using mutexes
+- Background sweeper thread to remove expired keys
+- Redis-like CLI commands: `SET`, `GET`, `DEL`, `EXPIRE`, `TTL`, `SETEX`