fixed grammar on doc.

If readers can gain additional pieces of  information on smart contracts, then  "more details" should be correct.

Author: Abdulkarim4u

docs/introduction-to-smart-contracts.rst

@@ -10,7 +10,7 @@ A Simple Smart Contract
 
 Let us begin with a basic example that sets the value of a variable and exposes
 it for other contracts to access. It is fine if you do not understand
-everything right now, we will go into more detail later.
+everything right now, we will go into more details later.
 
 Storage Example
 ===============