#349: Corrected capitalization of conformance language in prefetch description

Author: brynrhodes

docs/specification/1.0.md

@@ -270,7 +270,7 @@ Note that the missing `u` key indicates that either the EHR has decided not to s
 
 #### Prefetch query restrictions
 
-To reduce the implementation burden on EHRs that support CDS Services, CDS Hooks recommends that prefetch queries only use a subset of the full functionality available in the FHIR specification. Valid prefetch URLs should only contain:
+To reduce the implementation burden on EHRs that support CDS Services, CDS Hooks recommends that prefetch queries only use a subset of the full functionality available in the FHIR specification. Valid prefetch URLs SHOULD only contain:
 
 * _instance_ level [read](https://www.hl7.org/fhir/http.html#read) interactions (for resources with known ids such as `Patient` and `Practitioner`)
 * _type_ level [search](https://www.hl7.org/fhir/http.html#search) interactions