Fixing verb agreement, reverting one instance of document to definition

Author: earth2marsh

versions/3.0.md

@@ -67,7 +67,7 @@ An OpenAPI definition can then be used by documentation generation tools to disp
 ## Definitions
 
 ##### <a name="oasDocument"></a>OpenAPI Document
-A document (or set of documents) that define or describe an API. An OpenAPI document uses and conforms to the OpenAPI Specification.
+A document (or set of documents) that defines or describes an API. An OpenAPI definition uses and conforms to the OpenAPI Specification.
 
 ##### <a name="pathTemplating"></a>Path Templating
 Path templating refers to the usage of curly braces ({}) to mark a section of a URL path as replaceable using path parameters.