[docs]: Need migration guide RAPID 1-->2

[c-h-david]

What would you like to suggest?

It would be helpful for existing users of RAPID1 to have a place where they can read about how to transform the previous input, configuration file, program names into RAPID2 format. Along with a way to check that new output is same as old output.

Let us ensure open source development is sustainable!

• I have looked at previous GitHub issues and this enhancement has
  not yet been proposed.

• I have read
  CODE_OF_COLLAB.md
  and agree to the terms.

• I understand from
  CONTRIBUTING.md
  that a response or resolution to my request is not guaranteed.