Update README.md

Author: michael-spengler

README.md

@@ -1,6 +1,9 @@
 # Merkle Tree 
 
-You can use this to proof a specific element is available at a specific index within an array in an efficient way.
+Merkle Trees became especially famous in the context of Bitcoin's Simple Payment Verification - see chapter 8 in the [Bitcoin Whitepaper](https://bitcoin.org/bitcoin.pdf).  
+
+In general you can use them to proof that a specific element is available at a specific index within an array (block, ...).  
+
 
 ## Usage Example
 
@@ -26,4 +29,4 @@ const isValid = merkleTree.verify(proof, investigatedEntryHashed, rootHash, exam
 if (isValid) {
     console.log(`we can be pretty sure that ${investigatedEntry} is in the array at index: ${exampleArray.indexOf(investigatedEntry)}`)
 } 
-```
+```