Note: Doc team updates the current version of the documentation and the
two previous versions (n-2), but we address *only high-priority, or
customer-reported issues* for -2 releases in support.
Describe the changes in the doc and link to your dev story:

1. - [x] Mandatory: Add the required version to the Fix version/s field.

2. - [x] Mandatory: Choose the type of documentation change or review.

• [ ] We need to update to an existing topic

• [x] We need to add a new document to an existing section

This belongs in the search section of the docs, most likely around here (link is from our 2.15 docs):
https://docs.redhat.com/en/documentation/red_hat_advanced_cluster_management_for_kubernetes/2.15/html/search/acm-search#customize-search-service

• [ ] We need a whole new section; this is a function not
  documented before and doesn't belong in any current section

• [ ] We need an Operator Advisory review and approval

• [ ] We need a z-Stream (Errata) Advisory and Release note for
  MCE and/or ACM

3. - [x] Mandatory: Find the link to where the documentation update
should go and add it to the recommended changes. You can either use the
published doc or the staged repo for this step:

Note: As the feature and doc is understood, this recommendation may
change. If this is new documentation, link to the section where you think
it should be placed.

Customer Portal published version

https://docs.redhat.com/en/documentation/red_hat_advanced_cluster_management_for_kubernetes/2.12

Doc staged repo within the ACM Workspace:
https://github.com/stolostron/rhacm-docs

4. - [x] Mandatory for GA content:

• [x] Add steps, the diff, known issue, and/or other important
  conceptual information in the following space:

https://docs.redhat.com/en/documentation/red_hat_advanced_cluster_management_for_kubernetes/2.15/html/search/acm-search#customize-search-service

^ In this section, we document how users can add persistent storage to search.  

See the story where we implemented an alert if the search PVC is not present - if the system is busy enough, we will now generate a critical prometheus alert on the system if the user has not configured a PVC for search.

We can probably add a note somewhere in the above section for 2.16 that this alert is there, and may fire under the following conditions:

The alert fires when:

- [The Search PVC is missing in namespace <open-cluster-management>] AND [Your environment is under heavy load OR a core search pod has crashed due to memory limits]

The underlying "Load" or "Crash" condition (default values are shown below):

- Scale: You are managing more than 10 clusters.
- App Load: You have a combined total of more than 100 Subscriptions and Argo ApplicationSets in your API server.
- Database Failure: The search-postgres pod was recently killed because it ran out of memory (OOMKilled).
- Indexer Failure: The search-indexer pod was recently killed because it ran out of memory (OOMKilled).
- Traffic Spike: The search indexer has seen a surge in requests (more than 100 new requests in the last 30 minutes)

When is the Alert Reset?  The alert will stop firing (reset) when either of these two things happens:
- The search PVC is created/restored: 
As soon as kube_persistentvolumeclaim_info appears in Prometheus for the  namespace OR The underlying "Load" or "Crash" clears.

• [x] *Add Required access level *(example, *Cluster
  Administrator*) for the user to complete the task:

The information above is informational, so no required access level.

• [ ] Add verification at the end of the task, how does the user
  verify success (a command to run or a result to see?)

• [x] Add link to dev story here:

https://issues.redhat.com/browse/ACM-2816

5. - [ ] Mandatory for bugs: What is the diff? Clearly define what the
problem is, what the change is, and link to the current documentation. Only
use this for a documentation bug.