(DOCSP-20729) Added additional prerequisites, about adding a deployment for Monitoring, to push live migration to Atlas (#5155) (#5157)

* (DOCSP-20729) Added additional prerequisites about adding for monitoring, to live migration to Atlas

* Apply copy review

* Tech review from Joanna

Author: JuliaMongo

source/tutorial/migrate-to-atlas.txt

@@ -24,7 +24,9 @@ Overview
 To live migrate data from the |mms|-monitored deployments to
 clusters in |service-short|, you:
 
-1. Prepare a cluster in |service|.
+1. Add your deployment to |mms| if you haven't already done so.
+#. Add credentials to Monitoring.
+#. Prepare a cluster in |service|.
 #. Provision a migration host in |mms| and connect |mms| to |service-short|.
 #. Start the live migration process in |service-short|.
 
@@ -40,13 +42,58 @@ Restrictions
 
 .. include:: /includes/migrate-to-atlas-restrictions.rst
 
+Supported Platforms
+-------------------
+
+The list of supported platforms depends on which type of live migration
+you are using:
+
+- For live migrations of MongoDB 6.0.5+ clusters monitored by |cloud-short| to |service-short|,
+  see :mongosync:`mongosync platforms </current/installation>` to review
+  the list of supported platforms for the migration host.
+
+- For live migrations of source clusters running MongoDB versions 4.4.x
+  or 5.0.x (FCV), the live migration to |service-short|
+  :ref:`is supported <live-migration-host-supported-platforms>` for all
+  platforms on which you can provision a migration host.
+
+  Provisioning of the migration host is not supported on Windows or macOS.
+  You can still live migrate your data from a Windows-based deployment
+  to |service-short| if you provision your migration host on one of its
+  supported platforms. You can't live migrate your data from a macOS-based
+  deployment to |service-short|.
+
 .. _lm-prereqs:
 
 Prerequisites
 -------------
 
 Before you begin the live migration process, follow these prerequisites.
 
+Add Your Deployment to |mms|
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Follow the procedure to :ref:`add-existing-mongodb-hosts`. 
+
+Add Credentials for Monitoring
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When you add your  deployment to |mms|, you need to add credentials for Monitoring only,  not for Automation or Backup. Adding your deployment for
+Monitoring  imports your deployment's metadata into |mms| to help with the live migration process. It doesn't import your deployment's actual data. To
+learn more about authentication credentials, see :ref:`add-existing-mongodb-processes-auth`.
+
+To add credentials for :ref:`Monitoring <monitoring-functional-overview>`:
+
+1. Create the credentials to the deployment. See 
+   :ref:`Required Access for Monitoring <mms-req-cred-monitoring>`.
+#. Add the credentials based on your project's authentication mechanism. 
+   See :ref:`add-auth-credentials-imported-deployment`. 
+
+.. note::
+
+   If you're adding your MongoDB deployment to monitoring so that you can live migrate it to |service-short|, you don't need to add credentials for 
+   Automation and Backup. To learn more, see :ref:`add-existing-mongodb-processes-auth`.
+
 .. cond:: onprem
 
    Request an External IP Address
@@ -174,25 +221,3 @@ Perform these tasks in |service-short|:
 
    - **Stage 3: Start the Migration**. In |service-short|, follow the
      steps in the wizard to start the live migration process.
-
-Supported Platforms
-~~~~~~~~~~~~~~~~~~~
-
-The list of supported platforms depends on which type of live migration
-you are using:
-
-- For live migrations of MongoDB 6.0.5+ clusters monitored by |cloud-short| to |service-short|,
-  see :mongosync:`mongosync platforms </current/installation>` to review
-  the list of supported platforms for the migration host.
-
-- For live migrations of source clusters running MongoDB versions 4.4.x
-  or 5.0.x (FCV), the live migration to |service-short|
-  :ref:`is supported <live-migration-host-supported-platforms>` for all
-  platforms on which you can provision a migration host.
-
-  Provisioning of the migration host is not supported on Windows or macOS.
-  You can still live migrate your data from a Windows-based deployment
-  to |service-short| if you provision your migration host on one of its
-  supported platforms. You can't live migrate your data from a macOS-based
-  deployment to |service-short|.
-