truncate insert description update

[naka-sho]

mode:tuncate_insert does not actually use the truncate statement, it executes the delete statement

https://github.com/embulk/embulk-output-jdbc/blob/dfb2192cd0162ac32b9111f1de7f28177e4cf902/embulk-output-jdbc/src/main/java/org/embulk/output/jdbc/AbstractJdbcOutputPlugin.java#L890-L897 https://github.com/embulk/embulk-output-jdbc/blob/dfb2192cd0162ac32b9111f1de7f28177e4cf902/embulk-output-jdbc/src/main/java/org/embulk/output/jdbc/JdbcOutputConnection.java#L386-L417 https://github.com/embulk/embulk-output-jdbc/blob/dfb2192cd0162ac32b9111f1de7f28177e4cf902/embulk-output-jdbc/src/main/java/org/embulk/output/jdbc/JdbcOutputConnection.java#L419-L427

https://github.com/embulk/embulk-output-jdbc/pull/321#issuecomment-1630121862

I have updated description to your comment's

[hiroyuki-sato]

@naka-sho Thank you for your work. Could you squash your commits?

[dmikurube]

I guess we can just merge this as-is without squashing. :)

[hiroyuki-sato]

@dmikurube Could you merge this? (I don't have the permission)

[dmikurube]

Thanks for your contribution. Let us merge this!