Improving Contract docs around forwarding amounts

[Torres-ssf]

The TS SDK Docs need some improvements around executing custom steps within a contract call that forwards an amount to a contract.

The problem:

When executing a contract call that requires amounts to be forwarded to the contract, the TS SDK can properly estimate, fund, and submit the transaction:

const forwardQuantity: CoinQuantity = {
  amount: bn(1000),
  assetId: TestAssetId.A.value,
};

await contract.functions
   .increment_counter(1)
   .callParams({
     forward: forwardQuantity,
   })
   .call();

However, when custom steps are required such as modifying the TransactionRequest before sending the transaction, the forward amount must be explicitly included during estimation and funding steps to ensure accurate cost calculations.

const forwardQuantity: CoinQuantity = {
  amount: bn(1000),
  assetId: TestAssetId.A.value,
};

const txRequest = await contract.functions
  .increment_counter(1)
  .callParams({
    forward: forwardQuantity,
  })
  .getTransactionRequest();

const txCost = await wallet.getTransactionCost(txRequest, {
  quantities: [forwardQuantity],
});

txRequest.gasLimit = txCost.gasUsed;
txRequest.maxFee = txCost.maxFee;

await wallet.fund(txRequest, txCost);

const tx = await wallet.sendTransaction(txRequest);
const txResult = await tx.waitForResult();

We need to update our docs to give our users a clearer understanding of handling custom transaction workflows when forwarding amounts in contract calls.