Fix "submission MediaType" typo in hyperschema examples

Author: Denis Laxalde

jsonschema-hyperschema.xml

@@ -1650,7 +1650,7 @@ Link: <https://schema.example.com/entry> rel=describedBy
                     a message for sending.  Since there is no concept of a retrievable,
                     replaceable, or deletable target resource, "targetSchema" and
                     "targetMediaType" are not used.  Non-representation payloads are
-                    described by "submissionSchema" and "submission MediaType".
+                    described by "submissionSchema" and "submissionMediaType".
                 </t>
                 <t>
                     Therefore, we use "submissionMediaType" to indicate a multipart/alternative