DOCSP-48695 -- Added consideration about openfiles limit for incremental backups (#829)

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- [DOCSP-48695](https://jira.mongodb.org/browse/DOCSP-48695)
-
[STAGING](https://deploy-preview-829--docs-ops-manager.netlify.app/core/backup-preparations/#backup-considerations)

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---------

Co-authored-by: kanchana-mongodb <[email protected]>
Co-authored-by: Aaron B <[email protected]>

Author: 3 people

source/core/backup-preparations.txt

@@ -407,8 +407,17 @@ scheduled snapshot time.
 
 .. include:: /release-notes/release-advisories/advisories-v4.2-backup.rst
 
+Incremental Backups
+~~~~~~~~~~~~~~~~~~~
+
+|mms| creates handles for each file in the database during  incremental backups. Ensure
+that the :manual:`open file limit
+</reference/ulimit/#std-label-recommended-ulimit-settings>` is greater than the number of
+files before taking an incremental backup. Alternatively, take a full backup instead of an
+incremental backup.
+
 Shared File System
-++++++++++++++++++
+~~~~~~~~~~~~~~~~~~
 
 .. include:: /includes/fact-shared-file-system-reqs.rst
 

source/release-notes/release-advisories/advisories-v4.2-backup.rst

@@ -70,7 +70,7 @@ Backup Features Supported at Present
 .. [#] |mms| requires a full backup for your first backup, after a
     snapshot has been deleted, and if the blockstore block size has
     been changed. Incremental backups reduce network transfer and
-    storage costs.
+    storage costs. 
 
     This feature works with: