Add Vale linting, new documentation, and content updates

Add Vale prose linting configuration with custom vocabulary for kernel.org
technical terms. This helps maintain consistent documentation style.

New documentation:
- email-hosting.rst: recommended email hosting options for maintainers
- korgalore.rst: documentation for the korgalore mailing list import tool
- lore-lei.rst: quick start guide for using lei with lore.kernel.org
- lore-archives.rst: archive collection instructions (moved from lore.rst)

Content updates:
- wiki.rst: document that wiki hosting has been discontinued
- gitolite/track_set.rst: document that the track subcommand is retired
- ksmap.rst: replace COVID-19 note with general video conference guidance
- linuxdev.rst: add application template and korgalore recommendation
- lore.rst: reorganize to describe the service and link to related docs

Add cross-references between related documents for better navigation.

Signed-off-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
Assisted-by: claude-opus-4-5-20251101