(DOCSP-39281) Adds new system alert description. (#212)

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- [DOCSP-39281](https://jira.mongodb.org/browse/DOCSP-39281)
-
[STAGING](https://preview-mongodberabilmdb.gatsbyjs.io/ops-manager/DOCSP-39281/core/system-alerts/#database-process)

- [LATEST BUILD
LOG](https://workerpool-boxgs.mongodbstitch.com/pages/job.html?collName=queue&jobId=664cfa85cf5bec1c29788852)

### Self-Review Checklist

- [x]
[Define](https://wiki.corp.mongodb.com/display/DE/Taxonomy+tagging+instructions)
taxonomy
[values](https://wiki.corp.mongodb.com/display/DE/Docs+Taxonomy) at top
of page.
- [x] Add genre facets (tutorial or reference), as in this [example
PR](10gen/cloud-docs#5042).
- [ ] Add programmingLanguage (if necessary).
- [ ] Add meta keywords (if necessary).
- [x] Resolve any new warnings or errors in the build.
- [x] Proofread for spelling and grammatical errors.
- [x] Check staging for rendering issues.
- [x] Confirm links are working.

Author: erabil-mdb

source/core/system-alerts.txt

@@ -4,6 +4,10 @@ Manage System Alerts
 
 .. default-domain:: mongodb
 
+.. facet::
+   :name: genre
+   :values: tutorial
+
 .. contents:: On this page
    :local:
    :backlinks: none
@@ -283,6 +287,12 @@ Database Process
      - .. alert:: Successfully connected to a database backing the system
      - 
 
+   * - ``BACKINGDB_DEFAULTRW_CONCERN_VERIFICATION_FAILED``
+     - .. alert:: AppDB default Read/Write concerns are not set to recommended values
+     - Sent when the :manual:`read concern </reference/read-concern-local/>` for 
+       the :ref:`backing databases <backing-database>` is *not* ``"local"`` and 
+       the :manual:`write concern </reference/write-concern/>` is *not* ``w: "majority"``. 
+
 Log
 ~~~