Get started: Add instructions for Void Linux (#5921)

## Description

Add instructions to install beets on Void Linux to the get started
section.

Author: semohr

docs/changelog.rst

@@ -117,6 +117,7 @@ Other changes:
 - Refactored library.py file by splitting it into multiple modules within the
   beets/library directory.
 - Added a test to check that all plugins can be imported without errors.
+- :doc:`/guides/main`: Add instructions to install beets on Void Linux.
 
 2.3.1 (May 14, 2025)
 --------------------

docs/guides/main.rst

@@ -26,6 +26,8 @@ You will need Python. Beets works on Python 3.8 or later.
   which will probably set your computer on fire.)
 - On **Alpine Linux**, `beets is in the community repository <alpine package_>`_
   and can be installed with ``apk add beets``.
+- On **Void Linux**, `beets is in the official repository <void package_>`_ and
+  can be installed with ``xbps-install -S beets``.
 - For **Gentoo Linux**, beets is in Portage as ``media-sound/beets``. Just run
   ``emerge beets`` to install. There are several USE flags available for
   optional plugin dependencies.
@@ -61,6 +63,8 @@ You will need Python. Beets works on Python 3.8 or later.
 
 .. _ubuntu details: https://launchpad.net/ubuntu/+source/beets
 
+.. _void package: https://github.com/void-linux/void-packages/tree/master/srcpkgs/beets
+
 If you have pip_, just say ``pip install beets`` (or ``pip install --user
 beets`` if you run into permissions problems).