Merge branch 'more-links-to-each-batch-in-background-migrations-docs' into 'master'

Minor tweaks/links for batched_background_migrations.md

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/169657



Merged-by: Krasimir Angelov <kangelov@gitlab.com>
Approved-by: Krasimir Angelov <kangelov@gitlab.com>
Co-authored-by: Dylan Griffith <dyl.griffith@gmail.com>

doc/development/database/batched_background_migrations.md

@@ -370,10 +370,11 @@ end
 #### Using a composite or partial index to iterate a subset of the table
 
 When applying additional filters, it is important to ensure they are properly
-covered by an index to optimize `EachBatch` performance.
+[covered by an index](iterating_tables_in_batches.md#example-2-iteration-with-filters)
+to optimize `EachBatch` performance.
 In the below examples we need an index on `(type, id)` or `id WHERE type IS NULL`
 to support the filters. See
-[the `EachBatch` documentation for more information](iterating_tables_in_batches.md).
+the [`EachBatch` documentation](iterating_tables_in_batches.md) for more information.
 
 If you have a suitable index and you want to iterate only a subset of the table
 you can apply a `where` clause before the `each_batch` like: