Converted Online Index operations limitation into a warning/note (#36191)

* Converted Online Index operations limitation into a warning/note

---------

Co-authored-by: Randolph West MSFT <97149825+rwestMSFT@users.noreply.github.com>

Author: nzagorac-ms

docs/relational-databases/track-changes/change-event-streaming/configure.md

@@ -551,7 +551,6 @@ The following limitations apply when using CES with Azure SQL Database:
 - A table can belong to only one streaming group. You can't stream the same table to multiple destinations.
 - You can only configure user tables for CES. CES doesn't support streaming system tables.
 - You can configure up to 4,096 stream groups. Each stream group can include up to 40,000 tables.
-- [Online index operations](../../indexes/perform-index-operations-online.md) are not supported
 - While CES is enabled on a table, you can't add or drop a primary key constraint on that table.
 
 - `ALTER TABLE SWITCH PARTITION` isn't supported on tables configured for CES.
@@ -564,6 +563,9 @@ The following limitations apply when using CES with Azure SQL Database:
   - Graph tables
   - External tables
 
+> [!IMPORTANT]  
+> [Online index operations](../../indexes/perform-index-operations-online.md) can generate substantial amounts of transaction log records. CES must process significantly more data, which can result in increased event latency.
+
 ### Column-level limitations
 
 - CES doesn't support the following data types. Streaming skips columns of these types: