Add missing word

doc/ci/yaml/README.md

@@ -2012,7 +2012,7 @@ job:
 > Introduced in GitLab 8.9 and GitLab Runner v1.3.0.
 
 `expire_in` allows you to specify how long artifacts should live before they
-expire and therefore deleted, counting from the time they are uploaded and
+expire and are therefore deleted, counting from the time they are uploaded and
 stored on GitLab. If the expiry time is not defined, it defaults to the
 [instance wide setting](../../user/admin_area/settings/continuous_integration.md#default-artifacts-expiration-core-only)
 (30 days by default, forever on GitLab.com).