Fix links in update README

[ci skip]

doc/update/README.md

@@ -2,17 +2,20 @@ Depending on the installation method and your GitLab version, there are multiple
 
 ## Omnibus Packages
 
-- [Omnibus update guide](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/doc/update.md) contains the steps needed to update a GitLab [package](https://about.gitlab.com/downloads/).
+- [Omnibus update guide](http://doc.gitlab.com/omnibus/update/README.html)
+  contains the steps needed to update a GitLab
+  [package](https://about.gitlab.com/downloads/).
 
 ## Installation from source
 
 - [The individual upgrade guides](https://gitlab.com/gitlab-org/gitlab-ce/tree/master/doc/update) are for those who have installed GitLab from source.
-- [The CE to EE update guides](https://gitlab.com/subscribers/gitlab-ee/tree/master/doc/update) are for subscribers of the Enterprise Edition only. The steps are very similar to a version upgrade: stop the server, get the code, update config files for the new functionality, install libs and do migrations, update the init script, start the application and check the application status.
-- [Upgrader](upgrader.md) is an automatic ruby script that performs the update for installations from source.
-- [Patch versions](patch_versions.md) guide includes the steps needed for a patch version, eg. 6.2.0 to 6.2.1.
+- [The CE to EE update guides](https://gitlab.com/gitlab-org/gitlab-ee/tree/master/doc/update) are for subscribers of the Enterprise Edition only. The steps are very similar to a version upgrade: stop the server, get the code, update config files for the new functionality, install libs and do migrations, update the init script, start the application and check the application status.
+- [Patch versions](patch_versions.md) guide includes the steps needed for a
+  patch version, eg. 6.2.0 to 6.2.1.
 
 ## Miscellaneous
 
-- [MySQL to PostgreSQL](mysql_to_postgresql.md) guides you through migrating your database from MySQL to PostgreSQL.
+- [MySQL to PostgreSQL](mysql_to_postgresql.md) guides you through migrating
+  your database from MySQL to PostgreSQL.
 - [MySQL installation guide](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/install/database_mysql.md) contains additional information about configuring GitLab to work with a MySQL database.
 - [Restoring from backup after a failed upgrade](restore_after_failure.md)