Correct deep-pagination-optimization.md

[whaliendev]

In the section on deep pagination optimization recommendations, even with deferred joins and subqueries, the internal SQL statements will still result in deep pagination. These queries need to be rewritten to use the primary key index (id). Otherwise, there is no difference from the original SQL, and performance might even be worse.

[whaliendev]

Here are the evidence:

for subquery

for deferred join