DOCSP-47952: replicaSets[n].members[m]._id should be required-v7.0-backport (768) (#770)

# Backport

This will backport the following commits from `master` to `v7.0`:
- [DOCSP-47952: replicaSets[n].members[m]._id should be required
(#768)](10gen/docs-ops-manager#768)

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Author: jwilliams-mongo

source/includes/api/automation-configuration/replicaSets.rst

@@ -99,7 +99,7 @@ This field is required for deployments with replica sets.
 
    * - replicaSets[n].members[m]._id
      - integer
-     - Optional
+     - Required
      - Any positive integer that indicates the member of the replica
        set.