Add docs for recent changes

content/en/docs/19.0/concepts/query-rewriting.md

@@ -91,6 +91,7 @@ Here is a list of all the system variables that are handled by Vitess and how th
 | sql_select_limit                        | VitessAware    |
 | transaction_mode                        | VitessAware    |
 | ddl_strategy                            | VitessAware    |
+| foreign_key_checks                      | VitessAware    |
 | workload                                | VitessAware    |
 | charset                                 | VitessAware    |
 | names                                   | VitessAware    |
@@ -171,7 +172,6 @@ Here is a list of all the system variables that are handled by Vitess and how th
 | end_markers_in_json                     | ReservedConn   |
 | eq_range_index_dive_limit               | ReservedConn   |
 | explicit_defaults_for_timestamp         | ReservedConn   |
-| foreign_key_checks                      | ReservedConn   |
 | group_concat_max_len                    | ReservedConn   |
 | information_schema_stats_expiry         | ReservedConn   |
 | max_heap_table_size                     | ReservedConn   |

content/en/docs/19.0/reference/features/show.md

@@ -73,6 +73,17 @@ Example Output:
 +-------+----------+-------+------------+---------+------------------+------------+----------------------+
 ```
 
+* `SHOW VSCHEMA KEYSPACES` -- Information about Vschema information for all the keyspaces including the foreign key mode, whether the keyspace is sharded, and if there is an error in the VSchema for the keyspace.
+```shell
+Example Output:
++----------+---------+-------------+---------+
+| Keyspace | Sharded | Foreign Key | Comment |
++----------+---------+-------------+---------+
+| ks       | true    | managed     |         |
+| uks      | false   | managed     |         |
++----------+---------+-------------+---------+
+```
+
 * `SHOW VSCHEMA TABLES` -- A list of tables available in the current keyspace's vschema.
 ```shell
 Example Output for customer keyspace:

content/en/docs/19.0/user-guides/vschema-guide/foreign-keys.md

@@ -33,9 +33,9 @@ For more details on what operations Vitess performs for each type of DML, please
 #### Limitations
 
 - Currently, Vitess only supports shard-scoped foreign key constraints even in the `managed` mode. Support for cross-shard foreign keys is planned for a future release.
-- `UPDATE` statements only support updating to a literal value. For example, `UPDATE t1 SET col1 = 3 WHERE id = col + 1` is accepted, but `UPDATE t1 SET col1 = col + 3` is not.
 - [OnlineDDL](../../schema-changes/managed-online-schema-changes/) doesn't work well with tables that have foreign key constraints on them.
 - Some query syntaxes like `REPLACE INTO` and `INSERT INTO ... ON DUPLICATE KEY UPDATE` aren't supported.
+- Cyclic foreign keys are rejected by Vitess.
 
 ### Vitess Disallows Foreign Keys