Fix bad link for altenrative schema proposal (#1949)

* Fix bad link

* Use auto link markdown

Co-Authored-By: Carsten Brandt <mail@cebe.cc>

proposals/001_Alternative Schema Proposal.md

@@ -53,7 +53,7 @@ Examples of the use of the Alternative Schema capability is added to the OpenAPI
 
 ### Alternative Schema Registry
 
-Values used to populate the Alternative Schema Object are required to come from the Alternative Schema Registry. The preliminary Alternative Schema Registry is located at https://spec.openapis.org/registries/alternative-schema[https://spec.openapis.org/registries/alternative-schema].
+Values used to populate the Alternative Schema Object are required to come from the Alternative Schema Registry. The preliminary Alternative Schema Registry is located at <https://spec.openapis.org/registries/alternative-schema>.
 
 *** Note this is a placeholder registry. Don't take the values seriously. ***