[BUG] Missing documentation for `beanie.odm.BulkWriter`

[ProFatXuanAll]

Describe the bug
As titled.
The documentation should have an example for beanie.odm.BulkWriter as well.

To Reproduce
See the current (v1.25.0) documentation.

Expected behavior
Have documentation on beanie.odm.BulkWriter.

[Roman Right]

Thank you for the catch