found a keyword not in docment

[qiuwenhuifx]

Error Report

Please answer the following questions before submitting your issue. Thanks!

1. What is the URL/path of the document related to this issue?

https://docs.pingcap.com/zh/tidb/v5.1/keywords 2. How would you like to improve it?

alter table to_test_keyword add placement varchar(200); ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your TiDB version for the right syntax to use line 1 column 49 near "varchar(200)" alter table to_test_keyword add `placement` varchar(200); Query OK, 0 rows affected (0.51 sec)

[ran-huang]

@bb7133 Is this an undocumented keyword? We might need to add this to the docs