docs: [google-cloud-dataplex] Fix the comment for ignore_null field to clarify its applicability on data quality rules (#12141)

- [ ] Regenerate this pull request now. --- docs:Added documentation of page_size default and maximum value for ListEntries and RetrieveAspects PiperOrigin-RevId: 594334510 Source-Link: googleapis/googleapis@75c4411 Source-Link: googleapis/googleapis-gen@2551030 Copy-Tag: eyJwIjoicGFja2FnZXMvZ29vZ2xlLWNsb3VkLWRhdGFwbGV4Ly5Pd2xCb3QueWFtbCIsImgiOiIyNTUxMDMwN2IzZGQ3OWMwMDc3ODc3ODcyY2MxOWZjNWU2OTdiNWFhIn0= --------- Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: gcf-owl-bot[bot]

packages/google-cloud-dataplex/google/cloud/dataplex_v1/types/data_quality.py

@@ -437,7 +437,12 @@ class DataQualityRule(proto.Message):
  a rule, unless ``ignore_null`` is ``true``. In that case,
  such ``null`` rows are trivially considered passing.
 
- This field is only valid for row-level type rules.
+ This field is only valid for the following type of rules:
+
+ - RangeExpectation
+ - RegexExpectation
+ - SetExpectation
+ - UniquenessExpectation
  dimension (str):
  Required. The dimension a rule belongs to. Results are also
  aggregated at the dimension level. Supported dimensions are