Clarify that version header is only required with SSZ encoding (#118)

Author: nflaig

apis/builder/blinded_blocks.yaml

@@ -22,7 +22,7 @@ post:
         $ref: "../../builder-oapi.yaml#/components/schemas/ConsensusVersion"
       required: false
       name: Eth-Consensus-Version
-      description: "Version of the block being submitted"
+      description: "The active consensus version to which the block being submitted belongs. Required if request is SSZ encoded."
   requestBody:
     description: A `SignedBlindedBeaconBlock`.
     required: true

builder-oapi.yaml

@@ -108,6 +108,7 @@ components:
   headers:
     Eth-Consensus-Version:
       $ref: "./beacon-apis/beacon-node-oapi.yaml#/components/headers/Eth-Consensus-Version"
+      description: "The active consensus version to which the data belongs. Required if response is SSZ encoded."
       schema:
         $ref: "#/components/schemas/ConsensusVersion"