(DOCSP-30885) Describe groom/snapshot conflict, add link for context. (#201)

[JIRA](https://jira.mongodb.org/browse/DOCSP-30885)
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Author: lmkerbey-mdb

source/core/backup-preparations.txt

@@ -426,6 +426,18 @@ differently depending upon which snapshot store contains the snapshots:
        the groom job runs. |mms| can run concurrent groom jobs on S3
        snapshot stores.
 
+.. note::
+
+   Snapshot jobs and groom jobs can't run concurrently. If you
+   initiate a groom job while a snapshot job is running, the groom job
+   fails, and |onprem| logs an error and automatically retries the
+   groom job after the snapshot job completes. If you initiate a
+   snapshot job while a groom job is running, the snapshot job fails,
+   and |onprem| logs an error and retries the snapshot job after the
+   groom job completes.
+
+To learn more about groom jobs, see :ref:`Groom jobs <grooms-page>`.
+
 .. _namespaces-filter:
 
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