"Error Updating Issue" on gitlab-org/gitlab-ee

I've tried several times to update the recent issue i created (#4040 (closed)), to fix the formatting of the tasks lists. It allows me to click edit, and update the text, but when I click save, I get a red banner that reads: Error Updating Issue.

I've waited about 5 minutes, and tried again, and still get the error. The exact text input i'm trying to enter is as follows:

The various pieces of documentation for setting up GitLab HA are all over the place on the docs site, and it's difficult to know if I've even found them all, so there is no search results page.

Right now the best "landing page" for setting up HA is https://docs.gitlab.com/ee/administration/high_availability/README.html.

I propose that this page be improved to add additional information and links. Current problems or things
that need to be clarified are as follows:

* [ ]  No mention at all of [roles](https://docs.gitlab.com/omnibus/roles/README.html#roles), even when clicking on the redis bullet item
* [ ]  No mention of [database replication](https://docs.gitlab.com/ee/administration/high_availability/alpha_database.html#consul) even from the linked "configuring the database"
* [ ]  no mention _anywhere_ of recommendations around usage of `sidekiq_cluster` settings. I've [found in an issue](https://gitlab.com/gitlab-org/omnibus-gitlab/issues/2506) that it seems you can set up some nodes specifically to use `sidekiq_cluster` to process some of the queues.
* [ ]  Most "node" documentation pages don't show what settings should be _disabled_ in terms of other components for each node
* [ ]  No idea if [roles](https://docs.gitlab.com/omnibus/roles/README.html#roles) is just a redis thing, or if there are roles for the various database components, and front-end components. Every piece of language uses "for example" and uses `redis`, but the unanswered implication is that there is a full list of roles somewhere
* [ ]  There should be a link directly on the high availability landing page regarding HA lifecycle (deployment, upgrade, backups, etc...)
* [ ]  Add a link section on main High Availability describing GitLab Geo, possibly even adding it as a third bullet to the [Architecture](https://docs.gitlab.com/ee/administration/high_availability/README.html#architecture) section of that doc
* [ ]  Add a list of non-core components that can have their own nodes, and the configs (including omnibus) for each. Specifically i'm talking about Registry, Elasticsearch and any other component that has omnibus/config.yaml settings and is used natively in the UI.  
 - I know for example, that the registry settings can get a tad complex between the `gitlab_rails` configs, the `registry` settings, and `registry_nginx` settings, when trying to set it up on a node outside of the single-node architecture.
* [ ]  Add a topology image (in the manner of the existing examples) for an Implementation with scaled redis, postgres, and sidkiq nodes (any other scalable components?). 
* [ ]  Add a topology image for usage of replication of database and front-end that include Gitlab Geo