Set up Railway system tutorials

[michihdeu]

i.e. the rules how to draft and maintain rules: https://tmrail.teresco.org/devel/devel.php#systems (which is currently just a different deployment of the hwy page)

• Agree on rules, please refer to the forum
• Apply changes to the front end, i.e. devel.php
  • Either create a new raildevel.php page with subpages
  • Or integrate the rail-specific rules into the existing hwy description, i.e. just indicating diffs

As mentioned under TravelMapping/DataProcessing#595 (comment) + TravelMapping/DataProcessing#595 (comment)

[jteresco]

As this and related manual changes are made, each of the options @michihdeu mentions above might be better in a given circumstance. If a page for railways is totally different from the corresponding page for highways (or if a page is needed for railways that wasn't needed at all for highways), it's fine to create and link to a new page (like his raildevel.php example). If a significant amount of the text is the same but parts need to be customized for highways vs. railways, PHP if statements are probably better. There are lots of examples throughout the pages that already support highway, railway, and in some cases, ski trail versions.