The FHIR specification has a number of resources:
http://hl7.org/fhir/2018May/resourcelist.html
Suppose a doctor:
how would these things be recorded in FHIR (which resource type)? I don't see 'PatientOrder', 'PatientRecommendation', 'PatientIntervention', etc...
Your choices are CarePlan or ServiceRequest.
Note FHIR versioning: You should look at either http://hl7.org/fhir (for the current official release - STU3) or http://build.fhir.org (for the draft of the next release - R4). The 2018May was a frozen snapshot for ballot but won't be supported by any implementations.