Update the README with more context before the website link

Author: mo8it

README.md

@@ -1 +1,7 @@
-# ➡️ [rustlings.rust-lang.org](https://rustlings.rust-lang.org) ⬅️
+# [Rustlings](https://rustlings.rust-lang.org) 🦀
+
+Small exercises to get you used to reading and writing [Rust](https://www.rust-lang.org) code - _Recommended in parallel to reading [the official Rust book](https://doc.rust-lang.org/book) 📚️_
+
+Visit the **website** for a demo, info about setup and more:
+
+## ➡️ [rustlings.rust-lang.org](https://rustlings.rust-lang.org) ⬅️