rkt.md: Add link to advanced configuration

docs/executors/rkt.md

@@ -65,5 +65,10 @@ option to be specified in [`config.toml`][toml].
 along with enforcing [image verification](#image-verification) prevents
 all users from running any job.
 
+## Further configuration
+
+See [advanced configuration][advancedconfig]
+
 [yaml]: http://doc.gitlab.com/ce/ci/yaml/README.html
 [toml]: ../commands/README.md#configuration-file
+[advancedconfig]: ../configuration/advanced-configuration.md#the-runnersrkt-section