Add schema helpers

src/gmconfig_schema_utils.erl

@@ -791,7 +791,7 @@ expand_schema(S, S0) when is_map(S) ->
     %% https://json-schema.org/understanding-json-schema/structuring#dollarref
     %% When $id is used in a subschema, it indicates an embedded schema.
     %% The identifier for the embedded schema is the value of $id
-    %%resolved against the Base URI of the schema it appears in.
+    %% resolved against the Base URI of the schema it appears in.
     %% A schema document that includes embedded schemas is called a
     %% Compound Schema Document. Each schema with an $id in a
     %% Compound Schema Document is called a Schema Resource.