Update references to Terra's classes in docstrings

[adekusar-drl]

What is the expected enhancement?

Review all docstrings in the package and update references to Terra's classes. For instance, in the VQC documentation we reference ``ZZFeatureMap`` that is in qiskit.circuit.library. When the package documentation is generated, the reference becomes just a plain text. Such references should be replaced with cross references, that are replaced in the generated documentations with corresponding links. In this example, in the documentation ``ZZFeatureMap`` to be replaced with `:class:`~qiskit.circuit.library.ZZFeatureMap`. Then in the html documentation this cross reference will become a link to the corresponding class in Terra.

[AbdullahKazi500]

@adekusar-drl Can you explain what is to be done here in HTML Documentation

[adekusar-drl]

The point is to update docstrings across the module in a way that references to classes/methods/etc become clickable in the HTML documentation. For example, in the QuantumKernel source code it is written:

feature_map: Parameterized circuit to be used as the feature map. If None is given,
    the `ZZFeatureMap` is used with two qubits.

In the html documentation available here ZZFeatureMap is highlighted, but it is a clickable link. To make it clickable the text should formatted as :class:`~qiskit.circuit.library.ZZFeatureMap`. Same should be done in other references across the module.

[AbdullahKazi500]

For example, to create a clickable link to the ZZFeatureMap class in the qiskit.circuit.library module, you would format the text in your docstring as follows right
If None is given, the :class:`~qiskit.circuit.library.ZZFeatureMap` is used with two qubits

[adekusar-drl]

Yes, this is correct.

[AbdullahKazi500]

I Guess I Can try to work on this 3 issues The SVR and this one while waiting for Terra release

[adekusar-drl]

Ok, I assigned this issue to you as well. But if you don't have time to work on any of them, let me know.

[AbdullahKazi500]

Yes I will try to and keep you updated

[adekusar-drl]

@AbdullahKazi500 is there any progress here?

[AbdullahKazi500]

Hi @adekusar-drl I am working to Replace the existing plain text reference with the cross-reference format in each docstring.
and to Generate the package documentation to ensure the cross-referencing works correctly. definitely I will make a pull request soon no need to worry : )

[SamD-1998]

Is there something else that is yet to be completed in this issue?

[adekusar-drl]

Considering the lack of progress and the time passed since the last message, I think, it is an issue that anybody can give a try.

[woodsp-ibm]

Closed as done by #700