Docs: move collection-reporting hooks under collection hooks (fixes #…

[skprasadu]

Moves pytest_collectstart, pytest_make_collect_report, pytest_itemcollected,
pytest_collectreport, and pytest_deselected from “Reporting hooks” to a dedicated
“Hooks for reporting about collection” subsection under “Collection hooks”.

Closes #12658

Local check: tox -e docs

Note: this PR is intentionally minimal and only moves the relevant hooks; it does not attempt a broader docs re-organization.

[skprasadu]

I opened PR #14056 to make the minimal change for #12658 (moving the collection-reporting hooks into the Collection hooks section). I kept the scope intentionally small so it shouldn’t block broader doc-structure improvements—please go ahead with those.

[skprasadu]

Local tox -e docs passes. The Read the Docs preview build is using Sphinx 9.0.4 and fails in sphinxcontrib_trio with KeyError: 'autofunction'. The repo already pins sphinx<9 in doc/en/broken-dep-constraints.txt, so RTD likely isn’t honoring the constraints/requirements file used by tox. This seems unrelated to the hook move; happy to open a separate PR to align RTD installs with doc/en/requirements.txt if you want.