Fix a typo in getting started reference documentation
See
@@ -516,7 +516,7 @@ is required.
<2> Assert that the service produced the expected response.
<3> Document the call to the service, writing the snippets into a directory named `index`
(which is located beneath the configured output directory). The snippets are written by
-a `RestDocumentationResultHandler`. You can obtain an instance of this clas from the
+a `RestDocumentationResultHandler`. You can obtain an instance of this class from the
static `document` method on
`org.springframework.restdocs.mockmvc.MockMvcRestDocumentation`.
