add transaction info

src/celo/cel2-transaction-interfaces-example.md

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+
+
+# Transactions 
+
+## creating api
+
+### cip66
+
+The new transaction type for paying for gas in fee currencies cip66. 
+the TLDR is it denominiate fees in CELO instead of FeeToken, which makes is behavior 
+much more like eip1559 transactions. maxFeePerGas/MaxPriorityFee can now be calculated / built the exact same way as eip1559 transactions. But it has an additional field `maxFeePerFeeCurrency` which serves as the limit / a hedge against exchange rate risk. as the transaction is "billed" in native celo but paid in the fee token. 
+
+
+```typescript
+
+// Explicitly 
+// here the sender / dev must calculate the maxFeePerFeeCurrency by hand 
+// this is what https://github.com/celo-org/viem/pull/13 enables 
+sendTransaction({
+ ...typicalEIP1559TransactionParams,
+ feeCurrency: '0xTokenAddress',
+ maxFeePerFeeCurrency: 10000000n,
+})
+
+
+// Implicitly
+// Today this creates a cip64 transaction, eventually we'd like it to default
+// to creating a cip66 by calculating maxFeePerFeeCurrency for the user
+// this requires knowing and multiply together 
+// the maxFeePerGas, the gasLimit, and the exchange rate of CELO to feeToken. 
+sendTransaction({
+ ...typicalEIP1559TransactionParams,
+ feeCurrency: '0xTokenAddress',
+})
+```
+
+### op deposit transactions
+
+finally add the ability to serialize deposit transactions.
+
+```typescript
+sendTransaction({
+ from: '0x977f82a600a1414e583f7f13623f1ac5d58b1c0b',
+ sourceHash:
+ '0x18040f35752170c3339ddcd850f185c9cc46bdef4d6e1f2ab323f4d3d7104319',
+ type: 'deposit'
+})
+
+```
+
+this is of course not the same as actually building a deposit transaction, which would be part of celo inclusion in op-stack extensions. 
+
+
+## reading api
+
+The changes here are minimal and it come down to 
+
+1. dont add properties to transactions that dont exist on them (ie `feeCurrency` was added to transactions in viem which did not have have )
+
+2. add maxFeePerGas as optional property when it is on the args.
+
+
+`maxFeeInFeeCurrency?: bigint`
+`feeCurrency?: Address | undefined` // instead of or in addition to `null`.
+