File "rules" has instructional text as comments near top.

2) Convert all text files in repo to LF line ending form.
   Any checkout done with "rules" in play will convert the working
   tree to native line ending, while keeping repo as LF line ending.

* Add visible clearance when edit node or track segment,
  add parameter "show clearance for new or edited track with via area"
  in "Display options" menu.