PBM-1561 Revise known limitations for backups and restores (#302)

* PBM-1561 Revise known limitations for backups and restores

Updated limitations for selective backups and restores, including sharded collections and multi-collection transactions.

Author: radoslawszulgo

docs/features/known-limitations.md

@@ -5,15 +5,15 @@ PBM supports various backup and restore types. Some of them have known limitatio
 ## Selective backups and restores
 
 1. Only **logical** backups and restores are supported.
-2. Selective backups and restores are supported in sharded clusters for non-sharded collections starting with version 2.0.3. Sharded collections are supported starting with version 2.1.0. 
-3. Sharded time series collections are not supported.
-4. Multi-collection transactions are not yet supported for selective restore. However, if you use them and attempt a selective restore, it may break [ACID](../reference/glossary.md#acid) because not all operations with this transaction are restored. PBM applies oplog events that relate only to the specified namespaces(s). Thus, from the transaction's point of view, the data consistency may be broken.
+2. Selective backups and restores are supported in sharded clusters for non-sharded collections starting with version 2.0.3. Sharded collections are supported starting with version 2.1.0.
+3. Selective restore of sharded collections from either a full logical backup or a selective logical backup is not supported if the distribution of chunks in the backup differs from the distribution of chunks in the existing collection. The supported way to restore in this scenario is to drop the target collection before performing the selective restore, ensuring shard metadata is recreated consistently.
+4. Sharded time series collections are not supported.
+5. Multi-collection transactions are not yet supported for selective restore. However, if you use them and attempt a selective restore, it may break [ACID](../reference/glossary.md#acid) because not all operations with this transaction are restored. PBM applies oplog events that relate only to the specified namespaces(s). Thus, from the transaction's point of view, the data consistency may be broken.
 
     For example, you have a transaction that involves collections A and B. When you restore collection A, PBM replays oplog events only for collection A and ignores those related to collection B. As a result, the state of collection B remains unchanged and is no longer consistent with collection A. 
 
-5. System collections in ``admin``, ``config``, and ``local`` databases cannot be backed up and restored selectively. You must make a full backup and restore to include them.
-6. Selective point-in-time recovery is not supported for sharded clusters.
-
+6. System collections in ``admin``, ``config``, and ``local`` databases cannot be backed up and restored selectively. You must make a full backup and restore to include them.
+7. Selective point-in-time recovery is not supported for sharded clusters.
 
 ## Oplog slicing for point-in-time recovery