Fix version references in 8.8 to 8.9 update guide

[ci skip]

doc/update/8.8-to-8.9.md

@@ -120,7 +120,7 @@ will need to let gitlab-workhorse listen on a TCP port. You can do this
 via [/etc/default/gitlab].
 
 [Apache templates]: https://gitlab.com/gitlab-org/gitlab-recipes/tree/master/web-server/apache
-[/etc/default/gitlab]: https://gitlab.com/gitlab-org/gitlab-ce/blob/8-8-stable/lib/support/init.d/gitlab.default.example#L37
+[/etc/default/gitlab]: https://gitlab.com/gitlab-org/gitlab-ce/blob/8-9-stable/lib/support/init.d/gitlab.default.example#L37
 
 #### Init script
 
@@ -145,7 +145,7 @@ To make sure you didn't miss anything run a more thorough check:
 
 If all items are green, then congratulations, the upgrade is complete!
 
-## Things went south? Revert to previous version (8.7)
+## Things went south? Revert to previous version (8.8)
 
 ### 1. Revert the code to the previous version