Update indices for new extra_sidekiq_routing.md file

doc/administration/operations/index.md

@@ -21,6 +21,7 @@ Keep your GitLab instance up and running smoothly.
 - [Sidekiq MemoryKiller](sidekiq_memory_killer.md): Configure Sidekiq MemoryKiller
   to restart Sidekiq.
 - [Multiple Sidekiq processes](extra_sidekiq_processes.md): Configure multiple Sidekiq processes to ensure certain queues always have dedicated workers, no matter the number of jobs that need to be processed. **(FREE SELF)**
+- [Sidekiq routing rules](extra_sidekiq_routing.md): Configure the routing rules to route a job from a worker to a desirable queue. **(FREE SELF)**
 - [Puma](puma.md): Understand Puma and puma-worker-killer.
 - Speed up SSH operations by [Authorizing SSH users via a fast,
   indexed lookup to the GitLab database](fast_ssh_key_lookup.md), and/or

doc/administration/sidekiq.md

@@ -187,4 +187,5 @@ gitlab_rails['monitoring_whitelist'] = ['10.10.1.42', '127.0.0.1']
 Related Sidekiq configuration:
 
 1. [Extra Sidekiq processes](operations/extra_sidekiq_processes.md)
+1. [Extra Sidekiq routing](operations/extra_sidekiq_routing.md)
 1. [Using the GitLab-Sidekiq chart](https://docs.gitlab.com/charts/charts/gitlab/sidekiq/)