Prevent typedoc from detecting every index file as a module

[timothymcmackin]

The typedoc.json file has this line:

  "entryPoints": ["./packages/**"],

This make typedoc see every index file in packages/ as a package, at every level.

As a result, the output shows several incorrect packages:

This PR changes it so only folders at the base level of packages/ become packages in the output:

To test:

1. Load this PR
2. Run yarn install && yarn build && yarn doc
3. Look at the file doc/index.html and verify that it shows only the provider and NFT checkout packages.