Update entity.rst

[toci-to-ci]

query_builder option - more clear explained

[xabbuh]

I am not sure about this change. In the description of the query_builder option we have this:

The value of this option can either be a QueryBuilder object, a callable or null (which will load all entities). When using a callable, you will be passed the EntityRepository of the entity as the only argument and should return a QueryBuilder. Returning null in the Closure will result in loading all entities.

Maybe change this line to something like this:

Suggested change

	the `query_builder`_ option. Please note, that `query_builder` is used to compose data, not fetch real final results::
	the `query_builder`_ option (which must be a `QueryBuilder` object, a closure returning a `QueryBuilder` object or `null` to load all entities)::

[javiereguiluz]

I like a lot this proposal. @toci-to-ci do you like it too? If this is more clear for you now, we can merge this suggestion. Thanks.

[toci-to-ci]

@javiereguiluz There is a lot of questions (stackoverflow ie) WHY error apears when using 'query_builder', PPL are using EntityType in Form same as Repository and fetch data which generate error message. The sugestion of @xabbuch is OK, it is mentioned earlier in documentation how field can act,

I just want to point out, that 'query_builder' is different way to extract (prepare) data than typical EntityRepository

[javiereguiluz]

This is now merged. While merging it I reworded as suggested by @xabbuh.

[javiereguiluz]

Piotr, thanks for this contribution to make docs better.