docs: admin-guide: add some subsection headings

As part of the goal of bringing some order to this file, add subsection
headings to help readers find what they are looking for.

Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20241213182057.343527-3-corbet@lwn.net
This commit is contained in:
Jonathan Corbet 2024-12-13 11:20:53 -07:00
commit 2eb4e66cdd