[HUDI-4580][DOCS] Update docs of Spark SQL create table statement

[yihua]

Change Logs

This PR updates the docs of Spark SQL create table statement. Based on #4584, the create table statement for an existing Hudi table does not require partitioned by or options statement (options (primaryKey = 'id', preCombineField = 'ts') partitioned by (dt)), and it should be

create table hudi_existing_tbl using hudi
location '/tmp/hudi/hudi_existing_table';

Impact

Only docs update.

Risk level: none
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• Change Logs and Impact were stated clearly
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