Adds support to other invoice types and minor update to README

[darwintantuco]

• [x] Adds support for other invoice types:
  • invoice service
  • invoice professional
  • invoice time billing

(I follow current naming convention, similar to InvoiceItem)

• [x] Update docs to explicitly include redirect uri when creating myob client Encountered invalid_request error when running myob_client.get_access_code_url. Found out that redirect_uri is needed. It would be nice to see this in README.

[darwintantuco]

would be nice if someone can check this PR