Document that fees are implicit in Rosetta

### Context & versions
cardano-rosetta-java 1.3.x - Fee handling in UTXO model

### Problem
Need to clearly document that fees are implicit, not explicit operations.

### Key clarification
**Fees are implicit in UTXO models** - this is correct behavior:
- Fees = sum(inputs) - sum(outputs) - deposits + withdrawals + refunds
- No explicit fee operations needed
- Fees are "burned" (go to rewards virtual pot, not transferred between addresses)
- This is WHY explicit fee operations aren't needed

### Example with withdrawal
```
Stake account: 100 ADA rewards
Withdrawal: 100 ADA
Transaction fee: 0.17 ADA

Result:
- Stake balance: 0 (100 ADA withdrawn)
- Added to outputs: 100 ADA
- Fee comes from: inputs - outputs difference (NOT from withdrawal)
- If only withdrawal with no other inputs: transaction would fail (*double check)
```

### Tasks
- [ ] Document how to set implicit fees
- [ ] Explain the formula: fee = inputs - outputs - deposits + withdrawals + refunds
- [ ] Add examples showing fee calculation, also including with withdrawals