Add docs for formatTransaction

[Yuripetusko]

What is the type of issue?

Documentation is missing

What is the issue?

While this is a minor util, and there are a lot of undocumented utils like this. This is a follow up to a Discord question a user had on parsing rpc response where values are Hex. And I had to look through the code to find this util, as viem docs doesn't feature it

Where did you find it?

Here's a useful code that I found when looking for an util that fits a requirement as per Discord question

viem/src/utils/formatters/transaction.test.ts

Line 7 in 6949c2b

formatTransaction({

And here's a proof that it can't be found on the viem docs