Section 3.1.0.16 (http://hl7.org/fhir/2018May/http.html#capabilities) states:

In addition, there is another method to get the capability statement, using the HTTP OPTIONS command:

_OPTIONS [base] {?_format=[mime-type]} _

_However as of STU3, this method is deprecated, and will be removed in a future version. Using OPTIONS like this is not conformant with HTTP, and creates challenges for [cross-origin resource sharing

Since we are releasing normative for R4, this feels like a good time to remove this OPTIONS option.