Fix typo in SchemaDefRequirement section

Author: kinow

Process.yml

@@ -918,7 +918,7 @@ $graph:
   doc: |
     This field consists of an array of type definitions which must be used when
     interpreting the `inputs` and `outputs` fields.  When a `type` field
-    contain a IRI, the implementation must check if the type is defined in
+    contains a IRI, the implementation must check if the type is defined in
     `schemaDefs` and use that definition.  If the type is not found in
     `schemaDefs`, it is an error.  The entries in `schemaDefs` must be
     processed in the order listed such that later schema definitions may refer