Issue on docs

[yuanyong001]

Don't support flexible partial update when 'columns' is specified

[yuanyong001]

create table sink_aaaa(
ID INT,
AGE STRING NULL,
SEX STRING NULL,
ADDRESS STRING NULL,
PRIMARY KEY(ID) NOT ENFORCED
) WITH (
'connector' = 'doris',
'fenodes' = '192.168.21.96:8030',
'table.identifier' = 'rt_ods.ods_atz_t_no_log',
'username' = 'root',
'password' = 'abc123',
'sink.properties.format' = 'json',
'sink.properties.read_json_by_line' = 'true',
'sink.properties.escape_delimiters' = 'true',
-- Sink 配置
'sink.label-prefix' = 'oracle-sync-job-ogg-v646111400001111',
'sink.enable-delete' = 'true',
'sink.enable-2pc' = 'true',
-- 保留灵活部分列更新
'sink.properties.unique_key_update_mode' = 'UPDATE_FLEXIBLE_COLUMNS'
);
create table sink_aaa