Proposal: Add Merkle root example in MASM

Hi team, I'd like to add a simple Merkle root calculation example to demonstrate tree structures for state proofs. It uses stack operations to simulate hashing pairs of leaves.

Example code sketch:
begin
# Leaf values (4 leaf, push ke stack)
push.1
push.2
push.3
push.4

# Level 1: Hash leaf pairs (simulasi hash dengan mul + add)
dup.1 dup.3 mul add # hash leaf 1 & 2
dup.1 dup.3 mul add # hash leaf 3 & 4

drop.4 # drop leaf asli

# Level 2: Hash node pairs (root)
dup.1 dup.1 mul add # hash node 1 & 2

drop.2 # drop node intermediate

# Hasil root di stack atas
end

This could help builders learn about Miden's Merkle Patricia Trees. Feedback?

Look for existing MASM examples in the repository to understand the format and location. The example should be placed in a relevant directory, likely under examples/ or docs/. Test the provided code sketch in a Miden environment to ensure it works as described, then create a new file or add to an existing example collection.

Written by the indexing model from the issue text.