Merge pull request #6148 from EnterpriseDB/docs/edits_to_migration_portal_pr6124

Edits to Migration Portal: workaround for snapshot too old error PR6124

Author: ebgitelman

product_docs/docs/migration_portal/4/known_issues_notes.mdx

@@ -245,17 +245,17 @@ While using the Oracle default case, you may experience a lower compatibility ra
 -   The EDB DDL Extractor currently doesn't support the extraction of `ROLES`, `SYSTEM GRANTS ON ROLES`, `OBJECT GRANTS ON ROLES`, and `ROLE GRANTS` from Oracle 11g. This behavior results in error messages being written to the extracted files in the sections corresponding to these object types. These errors don't cause any issue in the assessment of these files by Migration Portal.
 -   The EDB DDL Extractor script may log `object "OBJECT_NAME" of type SYNONYM not found in schema "PUBLIC"` errors in the dependent objects section of the extracted file. This happens only if the user selects the option to extract dependent objects from an Oracle multi tenant environment where the Oracle database is a container database.
 
-### "Snapshot Too Old" Error
+### "Snapshot Too Old" error
 
-The EDB DDL Extractor displays the error “ORA-01555: snapshot too old“ at runtime when the database server generates a volume of transactions that cannot be properly processed by the UNDO tablespace.
+The EDB DDL Extractor displays the error “ORA-01555: snapshot too old“ at runtime when the database server generates a volume of transactions that can't be properly processed by the UNDO tablespace.
 
 When the database server generates undo transactions at a high rate, it can cause the server to run out of space to store undo data. Since the UNDO tablespace is implemented as a circular buffer, it starts overwriting older undo data blocks. Resolve this error and rerun the EDB DDL Extractor to ensure you extract the DDLs without any errors.
 
-To work around this error, increase the allocated space for the UNDO_RETENTION parameter.
+To work around this error, increase the allocated space for the `UNDO_RETENTION` parameter.
 
 First, check the currently allocated total space for undo operations and the currently free space:
 
-1.  Check the existing value of the UNDO_RETENTION parameter:
+1.  Check the existing value of the `UNDO_RETENTION` parameter:
 
     ```sql
     SELECT value FROM v$parameter WHERE name = 'undo_retention';
@@ -283,14 +283,14 @@ Next, determine the number of MB your environment requires and increase the allo
     ```
 
     !!!note 
-    The value reflects the number of undo blocks consumed during a 10-minute interval, then converted into MB.
+    The value reflects the number of undo blocks consumed during a 10-minute interval, converted to MB.
     !!!
 
 1.  Calculate the total number of MB your environment requires for the UNDO tablespace. For example, if the transaction volume generates X MB of undo data per minute, and the requirement is to retain the data for Y minutes:
 
     UNDO Space (MB) = X (MB/min) × Y (min)
 
-1.  Update the UNDO_RETENTION parameter according to the required space in MB. This example increases the storage space to 2400 MB.
+1.  Update the `UNDO_RETENTION` parameter according to the required space in MB. This example increases the storage space to 2400 MB:
 
     ```sql
     ALTER SYSTEM SET UNDO_RETENTION = 2400;