Add requirements documentation

[litlfred]

Please generate a set of requirements documents for a node package that deals with the fhir mapping language FML file period it should be able to take fhir mapping on which content and compile it to produce a Fire Resource as Jason which is a structure map

. It should also have the functionality that if you give it a reference to a structure map and the content that goes into it then it should be able to execute the structure map on the given contents. May be the case that the same structure map is used to execute multiple times and compile in time of stretching that should be taken into consideration when implementing

There should be a good API framework to cleanly separate the functionality .

one functionality is the retrieval of structure Maps period there could be a case in which the structure map is little bit from a directory relative to deployment comma or there could be a case in which URL from the canonical idea of the structure map is used to retrieve a reference structure map

all functionality should be described using open apis evolved for the API calls as this is intended to be deployed as part of a microservice architecture. That service should not be a part of this Library comma this library is intended to be used within larger application framework