Usage of dropdowns are breaking HTML anchor

[glemaitre]

While working on the release 1.3.1, I found the following warning:

- doc/modules/grid_search.rst:611: WARNING: Failed to create a cross reference. A title or caption not found: 'pipeline_nested_parameters'
- sklearn/feature_extraction/text.py:docstring of sklearn.feature_extraction.text.CountVectorizer:59: WARNING: Failed to create a cross reference. A title or caption not found: 'stop_words'
- sklearn/feature_extraction/text.py:docstring of sklearn.feature_extraction.text.HashingVectorizer:86: WARNING: Failed to create a cross reference. A title or caption not found: 'stop_words'
- sklearn/feature_extraction/text.py:docstring of sklearn.feature_extraction.text.TfidfVectorizer:71: WARNING: Failed to create a cross reference. A title or caption not found: 'stop_words' 

After investigation, those warnings a linked to the following pattern:

.. _anchor:

|details-start|
**Title**
|details-split|
Blabla
|details-end|

and when using

:ref:`anchor`

Sphinx failed to create the reference.

We need to investigate and to take into account this issue when reviewing the dropdown menu thingy.

ping @ArturoAmorQ

[glemaitre]

I assume that one way would be to solve this issue as well: #27127

[ogrisel]

We need to investigate and to take into account this issue when reviewing the dropdown menu thingy.

It's not about a drop-down menu but more about collapsed details sections right?

[glemaitre]

It's not about a drop-down menu but more about collapsed details sections right?

Yes. It is just that all PRs are calling this <details> thingy dropdown. We should probably rename those into collapse details that is what it is.