capitalize SHOULD for fhirService use of TLS

Fixes FHIR-28654

Author: isaacvetter

docs/specification/current.md

@@ -123,7 +123,7 @@ Field | Optionality | Type | Description
 ----- | ----- | ----- | --------
 `hook` | REQUIRED | *string* | The hook that triggered this CDS Service call. See [Hooks](#hooks).
 <nobr>`hookInstance`</nobr> | REQUIRED | *string* | A universally unique identifier (UUID) for this particular hook call (see more information below).
-`fhirServer` | OPTIONAL | *URL* | The base URL of the CDS Client's [FHIR](https://www.hl7.org/fhir/) server. If fhirAuthorization is provided, this field is REQUIRED.  The scheme should be `https`
+`fhirServer` | OPTIONAL | *URL* | The base URL of the CDS Client's [FHIR](https://www.hl7.org/fhir/) server. If fhirAuthorization is provided, this field is REQUIRED.  The scheme SHOULD be `https`.
 `fhirAuthorization` | OPTIONAL | *object* | A structure holding an [OAuth 2.0][OAuth 2.0] bearer access token granting the CDS Service access to FHIR resources, along with supplemental information relating to the token. See the [FHIR Resource Access](#fhir-resource-access) section for more information.
 `context` | REQUIRED | *object* | Hook-specific contextual data that the CDS service will need.<br />For example, with the `patient-view` hook this will include the FHIR identifier of the [Patient](https://www.hl7.org/fhir/patient.html) being viewed.  For details, see the Hooks specification page.
 `prefetch` | OPTIONAL | *object* | The FHIR data that was prefetched by the CDS Client (see more information below).