Documentation improvement

[kerrywei]

Issue To Be Solved

There are few things that are missing/incorrect in correct API doc. i.e.
https://github.com/onflow/flow-cadut/blob/main/docs/api.md#extractsignerscode -- this method is intended to be used on transactions, however the example provided supplies a script to the function and will always result in empty array returned

The SignerPair link https://github.com/onflow/flow-cadut/blob/main/docs/api.md#SignerPair is not pointing to any section (missing content)

extractContractParameters() is not documented

Suggestion

Perform a full audit on all documents (as the issues listed here is non-exhaustive) before promoting this tool to a wider audience