[PR #13529/40a1713d backport][8.4.x] docs: clarify comma-separated -p NAME,NAME2 limitations and recommend stable alternatives

[patchback]

This is a backport of PR #13529 as merged into main (40a1713).

Issue Body

Description
In the “Disabling plugins from autoloading” section, the docs show:

[pytest]
addopts = --disable-plugin-autoload -p NAME,NAME2

However, in practice this often fails with:

ImportError: Error importing plugin "testmon,sugar,xdist": No module named 'testmon,sugar,xdist'

This happens both when that line is placed in pytest.ini (due to ConfigParser + shlex.split behavior) and in Windows CMD/PowerShell (shell does not preserve the comma list as a single argument). Pytest ends up trying to import the entire comma-separated string as one module.

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Steps to Reproduce

1. Install pytest ≥8.4 and plugins pytest-sugar, pytest-xdist.

2. Create pytest.ini containing:

   [pytest]
   addopts = --disable-plugin-autoload -p sugar,xdist

3. Run in Windows CMD or PowerShell:

   pytest

4. Observe the ImportError.

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Actual Behavior

ImportError: Error importing plugin "sugar,xdist": No module named 'testmon,sugar,xdist'

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Expected Behavior
The doc’s example should note that a single -p NAME,NAME2 is not reliably split into two plugin names when used in pytest.ini or on Windows shells. Users need the following stable patterns:

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Suggested Documentation Update

[pytest]
addopts =
    --disable-plugin-autoload
    -p NAME
    -p NAME2

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Environment

• pytest version: e.g. 8.4.0
• OS: Windows 10/11 CMD & PowerShell
• Plugins installed: pytest-sugar, pytest-xdist

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By calling out these parsing pitfalls and offering clear alternatives, the docs will better match real-world behavior and save users from this confusing import error.