"Show countries at low zoom levels but states at higher zoom levels" manual example does not work

The "Show countries at low zoom levels but states at higher zoom levels" entry in the manual does not work since you can't join tiles with mismatched zoom layers. The example will give the following warning:
```
"Warning: mismatched maxzooms: 5 in states-Z4.mbtiles vs previous 3"
```

Start with the manual entry titled “Show countries at low zoom levels but states at higher zoom levels” and reproduce the example using its referenced tiles. Investigate the reported mismatched maxzooms warning; done means the documented example works as described without that warning.

Written by the indexing model from the issue text.