Use the proper Content-Type for a property of type string with contentEncoding

Author: commonism

versions/3.1.1.md

@@ -1574,7 +1574,7 @@ requestBody:
             type: object
             properties: {}
           profileImage:
-            # Content-Type for application-level encoded resource is `text/plain`
+            # Content-Type for properties with type string and contentEncoding is `application/octet-stream`
             type: string
             contentMediaType: image/png
             contentEncoding: base64