Missing documentation of DefaultCrudRepository

Nobody has claimed this yet.

## URL of the page

[https://loopback.io/doc/en/lb4/](https://loopback.io/doc/en/lb4/)

## Nature of the issue

There is no API documentation for DefaultCrudRepository which is a key class.
The only place where it can be found is:
https://marioestradarosa.github.io/loopback.io/doc/en/lb4/apidocs.repository.defaultcrudrepository.html

## Expected behavior

I expect to find the API documentation by searching for DefaultCrudRepository or by browsing to:
[https://loopback.io/doc/en/lb4/apidocs.index.html](https://loopback.io/doc/en/lb4/apidocs.index.html)
but here the entire [@loopback/repository](https://loopback.io/doc/en/lb4/apidocs.repository.html)
is missing.

## Actual behavior

When I search DefaultCrudRepository it finds 5 references but not the API specification.

Start by checking the LB4 API documentation index and the @loopback/repository page linked in the issue, then verify how DefaultCrudRepository is represented in the published docs. Done means the DefaultCrudRepository API specification and the rest of @loopback/repository are reachable from the index and searchable on the documentation site.

Written by the indexing model from the issue text.