Document Martin usage on switch2osm site

[nyurik]

https://switch2osm.org/serving-tiles/ does not mention Martin tile server. We should document Martin as a viable option there. The source code is at https://github.com/switch2osm/switch2osm

[reddynitish]

Withdrawn — I’m no longer planning to take this issue. Thanks!

[Exberg]

Hi — I'd like to take this one (the previous volunteer withdrew in the linked switch2osm thread). Plan: add a "Serving tiles with Martin" walkthrough to switch2osm's serving-tiles section, covering install (package/binary/docker), serving vector tiles from a PostGIS database (the same one the manual guides build), and serving pre-built MBTiles/PMTiles archives — plus link it from the serving-tiles index. I'll verify every command against a real Martin install before opening the PR, and cross-reference switch2osm#296 so it fits the vector-tile content direction.

[CommanderStorm]

I don't know why this issue attracts it, but this issue is not an free ticket to unilaterally vibe at switch2osm...