"Next" link from user_guide/io.rst goes to read_sql_table API page
I think that's because we include a `:toctree:` on line 4,832

```
.. autosummary::
    :toctree: ../reference/api/

    read_sql_table
    read_sql_query
    read_sql
    DataFrame.to_sql
```

We likely don't need that `toctree`. Deleting it may fix the issue.

To check, we probably need to do a full doc build.